diff --git a/Makefile b/Makefile
--- a/Makefile
+++ b/Makefile
@@ -45,7 +45,7 @@ doc:
 clean:
 	-$(PYTHON) setup.py clean --all # ignore errors from this command
 	find . \( -name '*.py[cdo]' -o -name '*.so' \) -exec rm -f '{}' ';'
-	rm -f $(addprefix mercurial/,$(notdir $(wildcard mercurial/pure/*.py)))
+	rm -f $(addprefix mercurial/,$(notdir $(wildcard mercurial/pure/[a-z]*.py)))
 	rm -f MANIFEST MANIFEST.in tests/*.err
 	rm -rf build mercurial/locale
 	$(MAKE) -C doc clean