diff --git a/stdlib/Makefile b/stdlib/Makefile
index ae5e09f35..be613ffdf 100644
--- a/stdlib/Makefile
+++ b/stdlib/Makefile
@@ -9,4 +9,5 @@ all: $(ALL)
 
 clean:
 	rm -Rf *.s *.o *.i *~
+	pushd regression && make clean && popd
 
diff --git a/stdlib/regression/Makefile b/stdlib/regression/Makefile
index eb4f841ac..606ab2227 100644
--- a/stdlib/regression/Makefile
+++ b/stdlib/regression/Makefile
@@ -11,4 +11,4 @@ $(TESTS): %: %.expr
 	RC_RUNTIME=../../runtime $(RC) -I .. $< && ./$@ > $@.log && diff $@.log orig/$@.log
 
 clean:
-	$(RM) test*.log *.s *~ $(TESTS)
+	$(RM) test*.log *.s *~ $(TESTS) *.i