diff --git a/iFeatureOmegaCLI.py b/iFeatureOmegaCLI.py
index 8fbcc3f..6f8b4b1 100644
--- a/iFeatureOmegaCLI.py
+++ b/iFeatureOmegaCLI.py
@@ -3916,7 +3916,7 @@ class iDNA(Sequence):
     def __init__(self, file):
         super(iDNA, self).__init__(file=file)
         self.__default_para_dict = {
-            'Kmer type 1': {'kmer': 3},
+            'Kmer type 1': {'kmer': 4},
             'Kmer type 2': {'kmer': 3},
             'RCKmer type 1': {'kmer': 3},
             'RCKmer type 2': {'kmer': 3},