diff --git a/tests/test_normalizer.py b/tests/test_normalizer.py
index a6c16cb..3785e6c 100644
--- a/tests/test_normalizer.py
+++ b/tests/test_normalizer.py
@@ -84,6 +84,7 @@ def test_text_normalizer():
     assert std("he's like") == "he is like"
     assert std("she's been like") == "she has been like"
     assert std("10km") == "10 km"
+    assert std("10mm") == "10 mm"
     assert std("RC232") == "rc 232"
 
     assert (
diff --git a/whisper/normalizers/english.json b/whisper/normalizers/english.json
index bd84ae7..74a1c35 100644
--- a/whisper/normalizers/english.json
+++ b/whisper/normalizers/english.json
@@ -1737,6 +1737,5 @@
     "yoghurt": "yogurt",
     "yoghurts": "yogurts",
     "mhm": "hmm",
-    "mm": "hmm",
     "mmm": "hmm"
 }
\ No newline at end of file