diff --git a/resources/scripts/requirements.txt b/resources/scripts/requirements.txt
index caa419c2..b23f88ac 100644
--- a/resources/scripts/requirements.txt
+++ b/resources/scripts/requirements.txt
@@ -6,3 +6,4 @@ fontmake[repacker]==3.8.1
 # our scripts import it directly, so we list it among the top-level requirements.
 fonttools
 lxml
+cdifflib
diff --git a/resources/scripts/ttx_diff.py b/resources/scripts/ttx_diff.py
index 73ac2993..0c5db2fc 100755
--- a/resources/scripts/ttx_diff.py
+++ b/resources/scripts/ttx_diff.py
@@ -42,7 +42,7 @@
 import shutil
 import subprocess
 import sys
-from difflib import SequenceMatcher
+from cdifflib import CSequenceMatcher as SequenceMatcher
 from typing import MutableSequence