diff --git a/tests/hghave.py b/tests/hghave.py
--- a/tests/hghave.py
+++ b/tests/hghave.py
@@ -613,7 +613,13 @@
 def has_clang_format():
     m = matchoutput('clang-format --version', br'clang-format version (\d+)')
     # style changed somewhere between 10.x and 11.x
-    return m and int(m.group(1)) >= 11
+    if m:
+        return int(m.group(1)) >= 11
+    # Allow users to have a trunk version installed; this assumes that they keep
+    # it up to date, unfortunately checking for that is difficult/impossible?
+    return matchoutput(
+        'clang-format --version', br'clang-format .*trunk \([0-9a-f]+\)'
+    )
 
 
 @check("jshint", "JSHint static code analysis tool")