diff --git a/.gitmodules b/.gitmodules
index b22feb37..bd07bd3d 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +1,6 @@
 [submodule "Carthage/Checkouts/OneTimePassword"]
 	path = Carthage/Checkouts/OneTimePassword
-	url = https://github.com/mattrubin/OneTimePassword.git
+	url = https://github.com/bmwalters/OneTimePassword.git
 [submodule "Carthage/Checkouts/xcconfigs"]
 	path = Carthage/Checkouts/xcconfigs
 	url = https://github.com/jspahrsummers/xcconfigs.git
diff --git a/Authenticator/Source/TokenEntryForm.swift b/Authenticator/Source/TokenEntryForm.swift
index b25a8491..bf5cb809 100644
--- a/Authenticator/Source/TokenEntryForm.swift
+++ b/Authenticator/Source/TokenEntryForm.swift
@@ -29,6 +29,7 @@ import Base32
 
 private let defaultTimerFactor = Generator.Factor.timer(period: 30)
 private let defaultCounterFactor = Generator.Factor.counter(0)
+private let steamguardFactor = Generator.Factor.timer(period: 30)
 
 struct TokenEntryForm: Component {
     private var issuer: String = ""
@@ -91,9 +92,10 @@ extension TokenEntryForm {
                     rows: !showsAdvancedOptions ? [] :
                         [
                             tokenTypeRowModel,
+                        ] + (tokenType == .steamguard ? [] : [
                             digitCountRowModel,
                             algorithmRowModel,
-                        ]
+                        ])
                 ),
             ],
             doneKeyAction: .submit
@@ -190,8 +192,16 @@ extension TokenEntryForm {
             self.name = name
         case let .secret(secret):
             self.secret = secret
+        case .tokenType(.steamguard):
+            self.tokenType = .steamguard
+            // All Steam Guard tokens use the following settings.
+            self.algorithm = .sha1
+            self.digitCount = 5
         case let .tokenType(tokenType):
             self.tokenType = tokenType
+            // The digit count may have been lowered by
+            // switching to Steam Guard, so clamp it.
+            self.digitCount = max(self.digitCount, 6)
         case let .digitCount(digitCount):
             self.digitCount = digitCount
         case let .algorithm(algorithm):
@@ -217,18 +227,25 @@ extension TokenEntryForm {
         }
 
         let factor: Generator.Factor
+        let representation: Generator.Representation
         switch tokenType {
         case .counter:
             factor = defaultCounterFactor
+            representation = .numeric
         case .timer:
             factor = defaultTimerFactor
+            representation = .numeric
+        case .steamguard:
+            factor = steamguardFactor
+            representation = .steamguard
         }
 
         guard let generator = Generator(
             factor: factor,
             secret: secretData,
             algorithm: algorithm,
-            digits: digitCount
+            digits: digitCount,
+            representation: representation
             ) else {
                 // This UI doesn't allow the user to create an invalid period or digit count,
                 // so a generic error message is acceptable here.
diff --git a/Authenticator/Source/TokenFormModels.swift b/Authenticator/Source/TokenFormModels.swift
index 88558bab..8b3d9467 100644
--- a/Authenticator/Source/TokenFormModels.swift
+++ b/Authenticator/Source/TokenFormModels.swift
@@ -47,7 +47,7 @@ enum TokenFormRowModel<Action>: Identifiable {
 }
 
 enum TokenType {
-    case counter, timer
+    case counter, timer, steamguard
 }
 
 extension TextFieldRowViewModel {
@@ -96,6 +96,7 @@ extension SegmentedControlRowViewModel {
         let options = [
             (title: "Time Based", value: TokenType.timer),
             (title: "Counter Based", value: TokenType.counter),
+            (title: "Steam Guard", value: TokenType.steamguard),
         ]
         self.init(options: options, value: value, changeAction: changeAction)
     }
diff --git a/Cartfile b/Cartfile
index 6dc032ec..1d8ab00d 100644
--- a/Cartfile
+++ b/Cartfile
@@ -1,4 +1,4 @@
 # Configuration for Carthage (https://github.com/Carthage/Carthage)
 
-github "mattrubin/OneTimePassword" ~> 3.1.4
+github "bmwalters/OneTimePassword" "feature/steamguard"
 github "SVProgressHUD/SVProgressHUD" ~> 2.0
diff --git a/Cartfile.resolved b/Cartfile.resolved
index 54abe02f..fbaf8858 100644
--- a/Cartfile.resolved
+++ b/Cartfile.resolved
@@ -1,5 +1,5 @@
 github "SVProgressHUD/SVProgressHUD" "2.2.5"
+github "bmwalters/OneTimePassword" "d00dd01e81d89d0dafd4770e4d50141733007584"
 github "jspahrsummers/xcconfigs" "1.0"
 github "mattrubin/Base32" "1.1.2+xcode10.2"
-github "mattrubin/OneTimePassword" "3.1.5"
 github "shinydevelopment/SimulatorStatusMagic" "2.4.1"
diff --git a/Carthage/Checkouts/OneTimePassword b/Carthage/Checkouts/OneTimePassword
index 8e325177..d00dd01e 160000
--- a/Carthage/Checkouts/OneTimePassword
+++ b/Carthage/Checkouts/OneTimePassword
@@ -1 +1 @@
-Subproject commit 8e32517705c140360b2b09e655ccd70f63e15fdc
+Subproject commit d00dd01e81d89d0dafd4770e4d50141733007584