diff --git a/CHANGELOG.md b/CHANGELOG.md
index 54b59a1..20f90b7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,45 @@
 
 # SmarterCSV 1.x Change Log
 
+## 1.13.0 (2024-11-06) ⚡ POTENTIALLY BREAKING ⚡
+  
+  CHANGED DEFAULT BEHAVIOR
+  ========================
+  The changes are to improve robustness and to reduce the risk of data loss
+
+  * implementing auto-detection of extra columns (thanks to James Fenley)
+
+  * improved handling of unbalanced quote_char in input ([issue 288](https://github.com/tilo/smarter_csv/issues/288)) thanks to Simon Rentzke), and ([issue 283](https://github.com/tilo/smarter_csv/issues/283)) thanks to James Fenley, Randall B, Matthew Kennedy)
+    -> SmarterCSV will now raise `SmarterCSV::MalformedCSV` for unbalanced quote_char.
+
+  * bugfix / improved handling of extra columns in input data ([issue 284](https://github.com/tilo/smarter_csv/issues/284)) (thanks to James Fenley)
+   
+    * previous behavior:
+      when a CSV row had more columns than listed in the header, the additional columns were ignored
+
+    * new behavior:
+      * new default behavior is to auto-generate additional headers, e.g. :column_7, :column_8, etc
+      * you can set option `:strict` to true in order to get a `SmarterCSV::MalformedCSV` exception instead
+
+  * setting `user_provided_headers` now implies `headers_in_file: false` ([issue 282](https://github.com/tilo/smarter_csv/issues/282))
+    
+    The option `user_provided_headers` can be used to specify headers when there are none in the input, OR to completely override headers that are in the input (file).
+
+    SmarterCSV is now using a safer default behavior.
+
+    * previous behavior:
+      Setting `user_provided_headers` did not change the default `headers_in_file: true`
+      If the input had no headers, this would cause the first line to be erroneously treated as a header, and the user could lose the first row of data.
+
+    * new behavior:
+      Setting `user_provided_headers` sets`headers_in_file: false`
+      a) Improved behavior if there was no header in the input data.
+      b) If there was a header in the input data, and `user_provided_headers` is used to override the headers in the file, then please explicitly specify `headers_in_file: true`, otherwise you will get an extra hash which includes the header data.
+
+    IF you set `user_provided_headers` and the file has a header, then provide `headers_in_file: true` to avoid getting that extra record.
+
+   * handling of numeric columns with leading zeroes, e.g. ZIP codes. ([issue #151](https://github.com/tilo/smarter_csv/issues/151) thanks to David Moles). `convert_values_to_numeric: { except: [:zip] }` will now return a string for that column instead.
+
 ## 1.12.1 (2024-07-10)
   * Improved column separator detection by ignoring quoted sections [#276](https://github.com/tilo/smarter_csv/pull/276) (thanks to Nicolas Castellanos)
 
diff --git a/CONTRIBUTORS.md b/CONTRIBUTORS.md
index f771736..8dc180e 100644
--- a/CONTRIBUTORS.md
+++ b/CONTRIBUTORS.md
@@ -54,3 +54,7 @@ A Big Thank you to everyone who filed issues, sent comments, and who contributed
  * [Kenton Hirowatari](https://github.com/hirowatari)
  * [Daniel Pepper](https://github.com/dpep)
  * [Nicolas Castellanos](https://github.com/nicastelo)
+ * [James Fenley](https://github.com/rex-remind101)
+ * [Simon Rentzke](https://github.com/simonrentzke)
+ * [Randall B](https://github.com/randall-coding)
+ * [Matthew Kennedy](https://github.com/MattKitmanLabs)
diff --git a/docs/data_transformations.md b/docs/data_transformations.md
index c1c5ded..20d9071 100644
--- a/docs/data_transformations.md
+++ b/docs/data_transformations.md
@@ -33,6 +33,8 @@ Here is an example of using `convert_values_to_numeric` for numbers with leading
    => [{:zip=>"00480"}, {:zip=>"51903"}, {:zip=>"12354"}, {:zip=>"02343"}]
 ```   
 
+This will return the column `:zip` as a string with all digits intact.
+
 ## Remove Zero Values
 `remove_zero_values` is disabled by default.
 When enabled, it removes key/value pairs which have a numeric value equal to zero.
diff --git a/docs/header_transformations.md b/docs/header_transformations.md
index 86af3b1..c397a57 100644
--- a/docs/header_transformations.md
+++ b/docs/header_transformations.md
@@ -64,6 +64,8 @@ If you want to have an underscore between the header and the number, you can set
    => [{:first_name=>"Carl", :middle_name=>"Edward", :last_name=>"Sagan"}]
 ```
 
+If you set `duplicate_header_suffix: nil`, you get the same behavior as earlier versions, which raised the `SmarterCSV::DuplicateHeaders` error.
+
 ## Key Mapping
 
 The above example already illustrates how intermediate keys can be mapped into something different.
diff --git a/docs/options.md b/docs/options.md
index fff28a1..e2f3f51 100644
--- a/docs/options.md
+++ b/docs/options.md
@@ -41,7 +41,7 @@
      | :skip_lines                 |   nil    | how many lines to skip before the first line or header line is processed             |
      | :comment_regexp             |   nil    | regular expression to ignore comment lines (see NOTE on CSV header), e.g./\A#/       |
      ---------------------------------------------------------------------------------------------------------------------------------
-     | :col_sep                    |   :auto   | column separator (default was ',')                                           |
+     | :col_sep                    |   :auto   | column separator (default was ',')                                                  |
      | :force_simple_split         |   false  | force simple splitting on :col_sep character for non-standard CSV-files.             |
      |                             |          | e.g. when :quote_char is not properly escaped                                        |
      | :row_sep                    |  :auto   | row separator or record separator (previous default was system's $/ , which defaulted to "\n") |
@@ -49,9 +49,10 @@
      | :auto_row_sep_chars         |   500    | How many characters to analyze when using `:row_sep => :auto`. nil or 0 means whole file. |
      | :quote_char                 |   '"'    | quotation character                                                                  |
      ---------------------------------------------------------------------------------------------------------------------------------
-     | :headers_in_file            |   true   | Whether or not the file contains headers as the first line.                          |
-     |                             |          | Important if the file does not contain headers,                                      |
-     |                             |          | otherwise you would lose the first line of data.                                     |
+     | :headers_in_file            |  true(1) | Whether or not the file contains headers as the first line.                          |
+     |                             |          | (1): if `user_provided_headers` is given, the default is `false`,                    |
+     |                             |          | unless you specify it to be explicitly `true`.                                       |
+     |                             |          | This prevents losing the first line of data, which is otherwise assumed to be a header. |
      | :duplicate_header_suffix    |   ''     | Adds numbers to duplicated headers and separates them by the given suffix.           |
      |                             |          | Set this to nil to raise `DuplicateHeaders` error instead (previous behavior)        |
      | :user_provided_headers      |   nil    | *careful with that axe!*                                                             |
@@ -61,6 +62,8 @@
      | :remove_empty_hashes        |   true   | remove / ignore any hashes which don't have any key/value pairs or all empty values  |
      | :verbose                    |   false  | print out line number while processing (to track down problems in input files)       |
      | :with_line_numbers          |   false  | add :csv_line_number to each data hash                                               |
+     | :missing_header_prefix      |  column_ | can be set to a string of your liking                                                |
+     | :strict                     |   false  | When set to `true`, extra columns will raise MalformedCSV exception                  |
      ---------------------------------------------------------------------------------------------------------------------------------
 
 Additional 1.x Options which may be replaced in 2.0
@@ -71,11 +74,11 @@ There have been a lot of 1-offs and feature creep around these options, and goin
      | Option                      | Default  |  Explanation                                                                         |
      ---------------------------------------------------------------------------------------------------------------------------------
      | :key_mapping                |   nil    | a hash which maps headers from the CSV file to keys in the result hash               |
-     | :silence_missing_keys        |   false  | ignore missing keys in `key_mapping`                                   |
-     |                             |          | if set to true: makes all mapped keys optional                         |
+     | :silence_missing_keys        |   false  | ignore missing keys in `key_mapping`                                                |
+     |                             |          | if set to true: makes all mapped keys optional                                       |
      |                             |          | if given an array, makes only the keys listed in it optional                         |
-     | :required_keys              |   nil    | An array. Specify the required names AFTER header transformation.                  |
-     | :required_headers           |   nil    | (DEPRECATED / renamed) Use `required_keys` instead                          |
+     | :required_keys              |   nil    | An array. Specify the required names AFTER header transformation.                    |
+     | :required_headers           |   nil    | (DEPRECATED / renamed) Use `required_keys` instead                                   |
      |                             |          | or an exception is raised   No validation if nil is given.                           |
      | :remove_unmapped_keys       |   false  | when using :key_mapping option, should non-mapped keys / columns be removed?         |
      | :downcase_header            |   true   | downcase all column headers                                                          |
diff --git a/ext/smarter_csv/smarter_csv.c b/ext/smarter_csv/smarter_csv.c
index 6f70320..76931e7 100644
--- a/ext/smarter_csv/smarter_csv.c
+++ b/ext/smarter_csv/smarter_csv.c
@@ -9,9 +9,10 @@
   #define true  ((bool)1)
 #endif
 
-/*
-   max_size: pass nil if no limit is specified
- */
+VALUE SmarterCSV = Qnil;
+VALUE eMalformedCSVError = Qnil;
+VALUE Parser = Qnil;
+
 static VALUE rb_parse_csv_line(VALUE self, VALUE line, VALUE col_sep, VALUE quote_char, VALUE max_size) {
   if (RB_TYPE_P(line, T_NIL) == 1) {
     return rb_ary_new();
@@ -24,7 +25,7 @@ static VALUE rb_parse_csv_line(VALUE self, VALUE line, VALUE col_sep, VALUE quot
   rb_encoding *encoding = rb_enc_get(line); /* get the encoding from the input line */
   char *startP = RSTRING_PTR(line); /* may not be null terminated */
   long line_len = RSTRING_LEN(line);
-  char *endP = startP + line_len ; /* points behind the string */
+  char *endP = startP + line_len; /* points behind the string */
   char *p = startP;
 
   char *col_sepP = RSTRING_PTR(col_sep);
@@ -39,18 +40,19 @@ static VALUE rb_parse_csv_line(VALUE self, VALUE line, VALUE col_sep, VALUE quot
   VALUE field;
   long i;
 
-  char prev_char = '\0'; // Store the previous character for comparison against an escape character
-  long backslash_count = 0; // to count consecutive backslash characters
+  /* Variables for escaped quote handling */
+  long backslash_count = 0;
+  bool in_quotes = false;
 
   while (p < endP) {
     /* does the remaining string start with col_sep ? */
     col_sep_found = true;
-    for(i=0; (i < col_sep_len) && (p+i < endP) ; i++) {
+    for(i=0; (i < col_sep_len) && (p+i < endP); i++) {
       col_sep_found = col_sep_found && (*(p+i) == *(col_sepP+i));
     }
-    /* if col_sep was found and we have even quotes */
-    if (col_sep_found && (quote_count % 2 == 0)) {
-      /* if max_size != nil && lements.size >= header_size */
+    /* if col_sep was found and we're not inside quotes */
+    if (col_sep_found && !in_quotes) {
+      /* if max_size != nil && elements.size >= header_size */
       if ((max_size != Qnil) && RARRAY_LEN(elements) >= NUM2INT(max_size)) {
         break;
       } else {
@@ -60,22 +62,30 @@ static VALUE rb_parse_csv_line(VALUE self, VALUE line, VALUE col_sep, VALUE quot
 
         p += col_sep_len;
         startP = p;
+        backslash_count = 0; // Reset backslash count at the start of a new field
       }
     } else {
       if (*p == '\\') {
         backslash_count++;
       } else {
-        if (*p == *quoteP && (backslash_count % 2 == 0)) {
-          quote_count++;
+        if (*p == *quoteP) {
+          if (backslash_count % 2 == 0) {
+            /* Even number of backslashes means quote is not escaped */
+            in_quotes = !in_quotes;
+          }
+          /* Else, quote is escaped; do nothing */
         }
-        backslash_count = 0; // no more consecutive backslash characters
+        backslash_count = 0; // Reset after any character other than backslash
       }
       p++;
     }
-
-    prev_char = *(p - 1); // Update the previous character
   } /* while */
 
+  /* Check for unclosed quotes at the end of the line */
+  if (in_quotes) {
+    rb_raise(eMalformedCSVError, "Unclosed quoted field detected in line: %s", StringValueCStr(line));
+  }
+
   /* check if the last part of the line needs to be processed */
   if ((max_size == Qnil) || RARRAY_LEN(elements) < NUM2INT(max_size)) {
     /* copy the remaining line as a field with original encoding onto the results */
@@ -86,12 +96,11 @@ static VALUE rb_parse_csv_line(VALUE self, VALUE line, VALUE col_sep, VALUE quot
   return elements;
 }
 
-VALUE SmarterCSV = Qnil;
-VALUE Parser = Qnil;
-
 void Init_smarter_csv(void) {
-  SmarterCSV = rb_define_module("SmarterCSV");
-  Parser = rb_define_module_under(SmarterCSV, "Parser");
+  // these modules and the error class are already defined in Ruby code, make them accessible:
+  SmarterCSV = rb_const_get(rb_cObject, rb_intern("SmarterCSV"));
+  Parser = rb_const_get(SmarterCSV, rb_intern("Parser"));
+  eMalformedCSVError = rb_const_get(SmarterCSV, rb_intern("MalformedCSV"));
 
   rb_define_module_function(Parser, "parse_csv_line_c", rb_parse_csv_line, 4);
 }
diff --git a/lib/smarter_csv/auto_detection.rb b/lib/smarter_csv/auto_detection.rb
index 31564f2..717ff4b 100644
--- a/lib/smarter_csv/auto_detection.rb
+++ b/lib/smarter_csv/auto_detection.rb
@@ -13,14 +13,13 @@ def guess_column_separator(filehandle, options)
       delimiters = [',', "\t", ';', ':', '|']
 
       line = nil
+      escaped_quote = Regexp.escape(options[:quote_char])
       has_header = options[:headers_in_file]
       candidates = Hash.new(0)
       count = has_header ? 1 : 5
       count.times do
         line = readline_with_counts(filehandle, options)
         delimiters.each do |d|
-          escaped_quote = Regexp.escape(options[:quote_char])
-
           # Count only non-quoted occurrences of the delimiter
           non_quoted_text = line.split(/#{escaped_quote}[^#{escaped_quote}]*#{escaped_quote}/).join
 
diff --git a/lib/smarter_csv/errors.rb b/lib/smarter_csv/errors.rb
index ffe8d7d..ad285d2 100644
--- a/lib/smarter_csv/errors.rb
+++ b/lib/smarter_csv/errors.rb
@@ -11,6 +11,7 @@ class DuplicateHeaders < SmarterCSVException; end
   class MissingKeys < SmarterCSVException; end # previously known as MissingHeaders
   class NoColSepDetected < SmarterCSVException; end
   class KeyMappingError < SmarterCSVException; end
+  class MalformedCSV < SmarterCSVException; end
   # Writer:
   class InvalidInputData < SmarterCSVException; end
 end
diff --git a/lib/smarter_csv/options.rb b/lib/smarter_csv/options.rb
index 1c89459..6686f8e 100644
--- a/lib/smarter_csv/options.rb
+++ b/lib/smarter_csv/options.rb
@@ -26,6 +26,7 @@ module Options
       invalid_byte_sequence: '',
       keep_original_headers: false,
       key_mapping: nil,
+      missing_header_prefix: 'column_',
       quote_char: '"',
       remove_empty_hashes: true,
       remove_empty_values: true,
@@ -37,6 +38,7 @@ module Options
       row_sep: :auto, # was: $/,
       silence_missing_keys: false,
       skip_lines: nil,
+      strict: false,
       strings_as_keys: false,
       strip_chars_from_headers: nil,
       strip_whitespace: true,
@@ -50,6 +52,18 @@ module Options
     def process_options(given_options = {})
       puts "User provided options:\n#{pp(given_options)}\n" if given_options[:verbose]
 
+      # Special case for :user_provided_headers:
+      #
+      # If we would use the default `headers_in_file: true`, and `:user_provided_headers` are given,
+      # we could lose the first data row
+      #
+      # We now err on the side of treating an actual header as data, rather than losing a data row.
+      #
+      if given_options[:user_provided_headers] && !given_options.keys.include?(:headers_in_file)
+        given_options[:headers_in_file] = false
+        puts "WARNING: setting `headers_in_file: false` as a precaution to not lose the first row. Set explicitly to `true` if you have headers."
+      end
+
       @options = DEFAULT_OPTIONS.dup.merge!(given_options)
 
       # fix invalid input
diff --git a/lib/smarter_csv/parser.rb b/lib/smarter_csv/parser.rb
index f038a4a..abe68c9 100644
--- a/lib/smarter_csv/parser.rb
+++ b/lib/smarter_csv/parser.rb
@@ -7,6 +7,8 @@ module Parser
     ###
     ### Thin wrapper around C-extension
     ###
+    ### NOTE: we are no longer passing-in header_size
+    ###
     def parse(line, options, header_size = nil)
       # puts "SmarterCSV.parse OPTIONS: #{options[:acceleration]}" if options[:verbose]
 
@@ -31,59 +33,83 @@ def parse(line, options, header_size = nil)
     # - we are not assuming that quotes inside a fields need to be doubled
     # - we are not assuming that all fields need to be quoted (0 is even)
     # - works with multi-char col_sep
-    # - if header_size is given, only up to header_size fields are parsed
     #
-    # We use header_size for parsing the body lines to make sure we always match the number of headers
-    # in case there are trailing col_sep characters in line
+    # NOTE: we are no longer passing-in header_size
     #
-    # Our convention is that empty fields are returned as empty strings, not as nil.
+    # - if header_size was given, only up to header_size fields are parsed
     #
+    #     We used header_size for parsing the body lines to make sure we always match the number of headers
+    #     in case there are trailing col_sep characters in line
     #
-    # the purpose of the max_size parameter is to handle a corner case where
-    # CSV lines contain more fields than the header.
-    # In which case the remaining fields in the line are ignored
+    #     the purpose of the max_size parameter was to handle a corner case where
+    #     CSV lines contain more fields than the header. In which case the remaining fields in the line were ignored
     #
+    # Our convention is that empty fields are returned as empty strings, not as nil.
+
     def parse_csv_line_ruby(line, options, header_size = nil)
-      return [] if line.nil?
+      return [[], 0] if line.nil?
 
       line_size = line.size
       col_sep = options[:col_sep]
       col_sep_size = col_sep.size
       quote = options[:quote_char]
-      quote_count = 0
       elements = []
       start = 0
       i = 0
 
-      previous_char = ''
+      backslash_count = 0
+      in_quotes = false
+
       while i < line_size
-        if line[i...i+col_sep_size] == col_sep && quote_count.even?
+        # Check if the current position matches the column separator and we're not inside quotes
+        if line[i...i+col_sep_size] == col_sep && !in_quotes
           break if !header_size.nil? && elements.size >= header_size
 
           elements << cleanup_quotes(line[start...i], quote)
-          previous_char = line[i]
-          i += col_sep.size
+          i += col_sep_size
           start = i
+          backslash_count = 0 # Reset backslash count at the start of a new field
         else
-          quote_count += 1 if line[i] == quote && previous_char != '\\'
-          previous_char = line[i]
+          if line[i] == '\\'
+            backslash_count += 1
+          else
+            if line[i] == quote
+              if backslash_count % 2 == 0
+                # Even number of backslashes means quote is not escaped
+                in_quotes = !in_quotes
+              end
+              # Else, quote is escaped; do nothing
+            end
+            backslash_count = 0 # Reset after any character other than backslash
+          end
           i += 1
         end
       end
-      elements << cleanup_quotes(line[start..-1], quote) if header_size.nil? || elements.size < header_size
+
+      # Check for unclosed quotes at the end of the line
+      if in_quotes
+        raise MalformedCSV, "Unclosed quoted field detected in line: #{line}"
+      end
+
+      # Process the remaining field
+      if header_size.nil? || elements.size < header_size
+        elements << cleanup_quotes(line[start..-1], quote)
+      end
+
       [elements, elements.size]
     end
 
     def cleanup_quotes(field, quote)
       return field if field.nil?
 
-      # return if field !~ /#{quote}/ # this check can probably eliminated
-
+      # Remove surrounding quotes if present
       if field.start_with?(quote) && field.end_with?(quote)
-        field.delete_prefix!(quote)
-        field.delete_suffix!(quote)
+        field = field[1..-2]
       end
-      field.gsub!("#{quote}#{quote}", quote)
+
+      # Replace double quotes with a single quote
+      field.gsub!("#{quote * 2}", quote)
+
       field
     end
   end
diff --git a/lib/smarter_csv/reader.rb b/lib/smarter_csv/reader.rb
index be0527f..c7f76b5 100644
--- a/lib/smarter_csv/reader.rb
+++ b/lib/smarter_csv/reader.rb
@@ -62,7 +62,8 @@ def process(&block) # rubocop:disable Lint/UnusedMethodArgument
 
         skip_lines(fh, options)
 
-        @headers, header_size = process_headers(fh, options)
+        # NOTE: we are no longer using header_size
+        @headers, _header_size = process_headers(fh, options)
         @headerA = @headers # @headerA is deprecated, use @headers
 
         puts "Effective headers:\n#{pp(@headers)}\n" if @verbose
@@ -97,14 +98,23 @@ def process(&block) # rubocop:disable Lint/UnusedMethodArgument
           multiline = count_quote_chars(line, options[:quote_char]).odd?
 
           while multiline
-            next_line = fh.readline(options[:row_sep])
-            next_line = enforce_utf8_encoding(next_line, options) if @enforce_utf8
-            line += next_line
-            @file_line_count += 1
-
-            break if fh.eof? # Exit loop if end of file is reached
-
-            multiline = count_quote_chars(line, options[:quote_char]).odd?
+            begin
+              next_line = fh.readline(options[:row_sep])
+              next_line = enforce_utf8_encoding(next_line, options) if @enforce_utf8
+              line += next_line
+              @file_line_count += 1
+
+              multiline = count_quote_chars(line, options[:quote_char]).odd?
+            rescue EOFError
+              # End of file reached. Check if quotes are balanced.
+              total_quotes = count_quote_chars(line, options[:quote_char])
+              if total_quotes.odd?
+                raise MalformedCSV, "Unclosed quoted field detected in multiline data"
+              else
+                # Quotes are balanced; proceed without raising an error.
+                break
+              end
+            end
           end
 
           # :nocov:
@@ -116,7 +126,18 @@ def process(&block) # rubocop:disable Lint/UnusedMethodArgument
           line.chomp!(options[:row_sep])
 
           # --- SPLIT LINE & DATA TRANSFORMATIONS ------------------------------------------------------------
-          dataA, _data_size = parse(line, options, header_size)
+          dataA, data_size = parse(line, options) # we parse the extra columns
+
+          if options[:strict]
+            raise SmarterCSV::HeaderSizeMismatch, "extra columns detected on line #{@file_line_count}"
+          else
+            # we create additional columns on-the-fly
+            current_size = @headers.size
+            while current_size < data_size
+              @headers << "#{options[:missing_header_prefix]}#{current_size + 1}".to_sym
+              current_size += 1
+            end
+          end
 
           dataA.map!{|x| x.strip} if options[:strip_whitespace]
 
diff --git a/lib/smarter_csv/version.rb b/lib/smarter_csv/version.rb
index df26db3..410fc6c 100644
--- a/lib/smarter_csv/version.rb
+++ b/lib/smarter_csv/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module SmarterCSV
-  VERSION = "1.12.1"
+  VERSION = "1.13.0"
 end
diff --git a/spec/features/converters/convert_values_to_numeric_spec.rb b/spec/features/converters/convert_values_to_numeric_spec.rb
index f61e95b..e24640b 100644
--- a/spec/features/converters/convert_values_to_numeric_spec.rb
+++ b/spec/features/converters/convert_values_to_numeric_spec.rb
@@ -26,12 +26,13 @@
   end
 
   it 'can be prevented for some keys' do
-    options = { convert_values_to_numeric: { except: :reference }}
+    options = { convert_values_to_numeric: { except: [:reference, :zip_code] }}
     data = SmarterCSV.process("#{fixture_path}/numeric.csv", options)
 
     data.each do |hash|
       expect(hash[:wealth]).to be_a_kind_of(Numeric) unless hash[:wealth].nil?
       expect(hash[:reference]).to be_a_kind_of(String) unless hash[:reference].nil?
+      expect(hash[:zip_code]).to be_a_kind_of(String) unless hash[:zip_code].nil?
     end
   end
 
diff --git a/spec/features/general/basic_spec.rb b/spec/features/general/basic_spec.rb
index 1ebbaf8..b1e56cf 100644
--- a/spec/features/general/basic_spec.rb
+++ b/spec/features/general/basic_spec.rb
@@ -48,8 +48,8 @@
           end
         end
 
-        context 'with full user_provided_headers' do
-          let(:options) { super().merge({user_provided_headers: %i[a b c d e f]}) }
+        context 'with correct cardinality user_provided_headers' do
+          let(:options) { super().merge({user_provided_headers: %i[a b c d e f], headers_in_file: true}) }
 
           it 'replaces headers with user_provided_headers' do
             data = reader.process
@@ -60,8 +60,41 @@
           end
         end
 
-        context 'with partial user_provided_headers' do
-          let(:options) { super().merge({user_provided_headers: %i[a b c d e]}) }
+        # We simulate that there is no existing header in the input, by skipping the first line.
+        # Because we don't provide `headers_in_file` in our options, they will be set to `false`.
+        #
+        context 'without headers_in_file, and with insufficient user_provided_headers' do
+          let(:options) { super().merge({user_provided_headers: %i[a b c d e], skip_lines: 1}) }
+
+          it 'processes all 5 data rows, automatically adds column_6' do
+            data = reader.process
+            expect(data.size).to eq 5
+          end
+
+          it 'has no raw_header' do
+            reader.process
+            expect(reader.raw_header).to eq nil # because there was no header in the input
+          end
+
+          it 'automatically adds a column_6 because the given headers were not sufficient' do
+            reader.process
+            expect(reader.headers).to eq %i[a b c d e column_6]
+          end
+
+          context 'when :strict is set' do
+            let(:options) { super().merge({user_provided_headers: %i[a b c d e], strict: true, skip_lines: 1}) }
+
+            it 'raises an exception if the number of user_provided_headers is incorrect' do
+              expect do
+                reader.process
+              end.to raise_exception(SmarterCSV::HeaderSizeMismatch)
+            end
+          end
+        end
+
+        # if there is an existing header in the input, the user_provided_headers must have same cardinality
+        context 'with incorrect cardinality of user_provided_headers' do
+          let(:options) { super().merge({user_provided_headers: %i[a b c d e], headers_in_file: true}) }
 
           it 'raises an exception if the number of user_provided_headers is incorrect' do
             expect do
@@ -71,7 +104,7 @@
         end
 
         context 'with empty user_provided_headers' do
-          let(:options) { super().merge({user_provided_headers: []}) }
+          let(:options) { super().merge({user_provided_headers: [], headers_in_file: true}) }
 
           it 'raises an exception if the user_provided_headers is empty' do
             expect do
@@ -80,10 +113,10 @@
           end
         end
 
-        context 'with incorrect user_provided_headers' do
-          let(:options) { super().merge({user_provided_headers: {}}) }
+        context 'with invalid user_provided_headers' do
+          let(:options) { super().merge({user_provided_headers: {}, headers_in_file: true}) }
 
-          it 'raises an exception if the user_provided_headers is of incorrect type' do
+          it 'raises an exception if the user_provided_headers is of invalid type' do
             expect do
               reader.process
             end.to raise_exception(SmarterCSV::IncorrectOption, /ERROR: incorrect format for user_provided_headers! Expecting array with headers/)
diff --git a/spec/features/header_handling/duplicate_headers_spec.rb b/spec/features/header_handling/duplicate_headers_spec.rb
index 6288e97..a45cfea 100644
--- a/spec/features/header_handling/duplicate_headers_spec.rb
+++ b/spec/features/header_handling/duplicate_headers_spec.rb
@@ -12,7 +12,7 @@
 
     it 'raises error when user_provided_headers with duplicates are given' do
       expect do
-        options = {user_provided_headers: %i[a b c d a]}
+        options = {user_provided_headers: %i[a b c d a], headers_in_file: false}
         SmarterCSV.process("#{fixture_path}/duplicate_headers.csv", options)
       end.to raise_exception(SmarterCSV::DuplicateHeaders)
     end
@@ -49,7 +49,7 @@
       end
 
       it 'raises when duplicate headers are given' do
-        options.merge!({user_provided_headers: %i[a b c a a]})
+        options.merge!({user_provided_headers: %i[a b c a a], headers_in_file: false})
         expect do
           SmarterCSV.process("#{fixture_path}/duplicate_headers.csv", options)
         end.to raise_exception(SmarterCSV::DuplicateHeaders)
@@ -76,7 +76,7 @@
       end
 
       it 'raises when duplicate headers are given' do
-        options.merge!({user_provided_headers: %i[a b c a a]})
+        options.merge!({user_provided_headers: %i[a b c a a], headers_in_file: false})
         expect do
           SmarterCSV.process("#{fixture_path}/duplicate_headers.csv", options)
         end.to raise_exception(SmarterCSV::DuplicateHeaders)
diff --git a/spec/features/special_cases/extra_columns_spec.rb b/spec/features/special_cases/extra_columns_spec.rb
new file mode 100644
index 0000000..17a17b8
--- /dev/null
+++ b/spec/features/special_cases/extra_columns_spec.rb
@@ -0,0 +1,109 @@
+# frozen_string_literal: true
+
+fixture_path = 'spec/fixtures'
+
+# when rows with extra columns are present, we want to be robust against this error, and we auto-generate headers
+#
+describe 'CSV file with more columns that shown in header' do
+  let(:csv_path) { "#{fixture_path}/extra_columns.csv" }
+
+  [true, false].each do |bool|
+    context "with#{bool ? ' C-' : 'out '}acceleration" do
+      let(:options) { { acceleration: bool } }
+      let(:reader) { SmarterCSV::Reader.new(csv_path, options) }
+
+      context "when strict mode" do
+        before do
+          options.merge!(strict: true)
+        end
+
+        it "raises an exception" do
+          expect{reader.process}.to raise_exception SmarterCSV::HeaderSizeMismatch, "extra columns detected on line 2"
+        end
+      end
+
+      it "reads all lines of the file" do
+        data = reader.process
+        expect(data.size).to eq 5
+      end
+
+      context "when default behavior" do
+        # default behavior is to remove empty values
+        # it finds column_11, but it is empty, and will not show up as a hash
+        it "generates all extra columns" do
+          reader.process
+          expect(reader.headers).to eq %i[one two three four five six column_7 column_8 column_9 column_10 column_11]
+        end
+
+        it "parses all rows correctly" do
+          data = reader.process
+          expect(data[0]).to eq({one: 1, two: 2, five: 5, column_8: 8, column_9: 9})
+          expect(data[1]).to eq({one: 1, two: 2, three: 3, four: 4, five: 5, six: 6})
+          expect(data[2]).to eq({one: 1, two: 2, three: 3, four: 4, five: 5, six: 6})
+          expect(data[3]).to eq({one: 1, column_10: 10})
+          expect(data[4]).to eq({one: 1, column_10: 10})
+        end
+      end
+
+      context "when keeping empty values" do
+        before do
+          options.merge!(remove_empty_values: false)
+        end
+
+        it "generates all extra columns" do
+          reader.process
+          expect(reader.headers).to eq %i[one two three four five six column_7 column_8 column_9 column_10 column_11]
+        end
+
+        it "parses all rows correctly" do
+          data = reader.process
+          expect(data[0]).to eq({one: 1, two: 2, three: '', four: '', five: 5, six: '', column_7: '', column_8: 8, column_9: 9})
+          expect(data[1]).to eq({one: 1, two: 2, three: 3, four: 4, five: 5, six: 6, column_7: nil, column_8: nil, column_9: nil})
+          expect(data[2]).to eq({one: 1, two: 2, three: 3, four: 4, five: 5, six: 6, column_7: '', column_8: nil, column_9: nil})
+          expect(data[3]).to eq({one: 1, two: '', three: '', four: '', five: '', six: '', column_7: '', column_8: '', column_9: '', column_10: 10})
+          expect(data[4]).to eq({one: 1, two: '', three: '', four: '', five: '', six: '', column_7: '', column_8: '', column_9: '', column_10: 10, column_11: ''})
+        end
+      end
+
+      context "when missing_header_prefix is changed" do
+        before do
+          options.merge!(missing_header_prefix: 'col_')
+        end
+
+        it "generates all extra columns" do
+          reader.process
+          expect(reader.headers).to eq %i[one two three four five six col_7 col_8 col_9 col_10 col_11]
+        end
+
+        it "parses all rows correctly" do
+          data = reader.process
+          expect(data[0]).to eq({one: 1, two: 2, five: 5, col_8: 8, col_9: 9})
+          expect(data[1]).to eq({one: 1, two: 2, three: 3, four: 4, five: 5, six: 6})
+          expect(data[2]).to eq({one: 1, two: 2, three: 3, four: 4, five: 5, six: 6})
+          expect(data[3]).to eq({one: 1, col_10: 10})
+          expect(data[4]).to eq({one: 1, col_10: 10})
+        end
+      end
+
+      context "when user did not provide enough headers manually" do
+        before do
+          options.merge!(headers_in_file: true, user_provided_headers: %i[a b c d e f])
+        end
+
+        it "generates all extra columns" do
+          reader.process
+          expect(reader.headers).to eq %i[a b c d e f column_7 column_8 column_9 column_10 column_11]
+        end
+
+        it "parses all rows correctly" do
+          data = reader.process
+          expect(data[0]).to eq({a: 1, b: 2, e: 5, column_8: 8, column_9: 9})
+          expect(data[1]).to eq({a: 1, b: 2, c: 3, d: 4, e: 5, f: 6})
+          expect(data[2]).to eq({a: 1, b: 2, c: 3, d: 4, e: 5, f: 6})
+          expect(data[3]).to eq({a: 1, column_10: 10})
+          expect(data[4]).to eq({a: 1, column_10: 10})
+        end
+      end
+    end
+  end
+end
diff --git a/spec/features/special_cases/malformed_spec.rb b/spec/features/special_cases/malformed_spec.rb
index dc94989..1df8143 100644
--- a/spec/features/special_cases/malformed_spec.rb
+++ b/spec/features/special_cases/malformed_spec.rb
@@ -3,23 +3,48 @@
 fixture_path = 'spec/fixtures'
 
 # according to RFC-4180 quotes inside of "words" shouldbe doubled, but our parser is robust against that.
-describe 'malformed CSV quotes' do
-  context "malformed quotes in header" do
-    let(:csv_path) { "#{fixture_path}/malformed_header.csv" }
-    it 'should be resilient against single quotes' do
-      data = SmarterCSV.process(csv_path)
-      expect(data[0]).to eq({name: "Arnold Schwarzenegger", dobdob: "1947-07-30"})
-      expect(data[1]).to eq({name: "Jeff Bridges", dobdob: "1949-12-04"})
-    end
-  end
 
-  context "malformed quotes in content" do
-    let(:csv_path) { "#{fixture_path}/malformed.csv" }
+[true, false].each do |bool|
+  describe "handling files with escaped quote chars with#{bool ? ' C-' : 'out '}acceleration" do
+    let(:options) { { acceleration: bool } }
+    let(:reader) { SmarterCSV::Reader.new(csv_path, options) }
+
+    describe 'malformed CSV quotes' do
+      context "malformed quotes in header" do
+        let(:csv_path) { "#{fixture_path}/malformed_header.csv" }
+        it 'should be resilient against single quotes' do
+          data = reader.process
+          expect(data[0]).to eq({name: "Arnold Schwarzenegger", dobdob: "1947-07-30"})
+          expect(data[1]).to eq({name: "Jeff Bridges", dobdob: "1949-12-04"})
+        end
+      end
+
+      context "malformed quotes in content" do
+        let(:csv_path) { "#{fixture_path}/malformed.csv" }
+
+        it 'should be resilient against single quotes' do
+          data = reader.process
+          expect(data[0]).to eq({name: "Arnold Schwarzenegger", dob: "1947-07-30"})
+          expect(data[1]).to eq({name: "Jeff \"the dude\" Bridges", dob: "1949-12-04"})
+        end
+      end
 
-    it 'should be resilient against single quotes' do
-      data = SmarterCSV.process(csv_path)
-      expect(data[0]).to eq({name: "Arnold Schwarzenegger", dob: "1947-07-30"})
-      expect(data[1]).to eq({name: "Jeff \"the dude\" Bridges", dob: "1949-12-04"})
+      context "malformed quotes in content" do
+        let(:csv_path) { "#{fixture_path}/malformed_data_eof.csv" }
+
+        it 'should raise MalformedCSV error' do
+          expect { reader.process }.to raise_error(SmarterCSV::MalformedCSV, "Unclosed quoted field detected in multiline data")
+        end
+      end
+
+      context "malformed quotes in content" do
+        let(:csv_path) { "#{fixture_path}/malformed_data_gobbled.csv" }
+
+        it 'should raise MalformedCSV error' do
+          expect { reader.process }.to raise_error(SmarterCSV::MalformedCSV, /Unclosed quoted field detected/)
+        end
+      end
     end
+
   end
 end
diff --git a/spec/fixtures/extra_columns.csv b/spec/fixtures/extra_columns.csv
new file mode 100644
index 0000000..2e3355b
--- /dev/null
+++ b/spec/fixtures/extra_columns.csv
@@ -0,0 +1,6 @@
+one,two,three,four,five,six
+1,2,,,5,,,8,9
+1,2,3,4,5,6
+1,2,3,4,5,6,
+1,,,,,,,,,10
+1,,,,,,,,,10,
diff --git a/spec/fixtures/malformed_data_eof.csv b/spec/fixtures/malformed_data_eof.csv
new file mode 100644
index 0000000..ebd4265
--- /dev/null
+++ b/spec/fixtures/malformed_data_eof.csv
@@ -0,0 +1,3 @@
+name,dob,height
+Arnold Schwarzenegger,1947-07-30,188
+Jeff Bridges,1949-12-04,"5
diff --git a/spec/fixtures/malformed_data_gobbled.csv b/spec/fixtures/malformed_data_gobbled.csv
new file mode 100644
index 0000000..92fb050
--- /dev/null
+++ b/spec/fixtures/malformed_data_gobbled.csv
@@ -0,0 +1,3 @@
+name,dob,height
+Arnold Schwarzenegger,1947-07-30,6'2"
+Jeff Bridges,1949-12-04,
diff --git a/spec/fixtures/numeric.csv b/spec/fixtures/numeric.csv
index 7d6e374..cd0f593 100644
--- a/spec/fixtures/numeric.csv
+++ b/spec/fixtures/numeric.csv
@@ -1,5 +1,5 @@
-First Name,Last Name,Reference, Wealth
-Dan,McAllister,0123,3.5
+First Name,Last Name,Reference, Wealth, Zip Code
+Dan,McAllister,0123,3.5,93456
 ,,,
-Miles,O'Brian,2345,3
-Nancy,Homes,2345,01
+Miles,O'Brian,2345,3,00223
+Nancy,Homes,2345,01,02343