diff --git a/identify/extensions.py b/identify/extensions.py
index 3a50915..30adb2f 100644
--- a/identify/extensions.py
+++ b/identify/extensions.py
@@ -58,6 +58,7 @@
     'dart': {'text', 'dart'},
     'dbc': {'text', 'dbc'},
     'def': {'text', 'def'},
+    'diff': {'text', 'diff'},
     'dll': {'binary'},
     'dtd': {'text', 'dtd'},
     'ear': {'binary', 'zip', 'jar'},