--- a/test_acid.py
+++ b/test_acid.py
@@ -36,7 +36,7 @@
     """Return file encoding."""
     try:
         with open(filename, 'rb') as input_file:
-            from lib2to3.pgen2 import tokenize as lib2to3_tokenize
+            from fissix.pgen2 import tokenize as lib2to3_tokenize
             encoding = lib2to3_tokenize.detect_encoding(input_file.readline)[0]
 
             # Check for correctness of encoding.