diff --git a/test/lua/Makefile.am b/test/lua/Makefile.am
index 91de535..ed8c5ae 100644
--- a/test/lua/Makefile.am
+++ b/test/lua/Makefile.am
@@ -22,7 +22,8 @@
 # Remove "MapType =" line to ignore some map bug for now
 stubs: ../ThriftTest.thrift $(THRIFT)
 	$(THRIFT) --gen lua $<
-	$(SED) -i 's/MapType =//g' gen-lua/ThriftTest_ttypes.lua
+	$(SED) -i.bak 's/MapType =//g' gen-lua/ThriftTest_ttypes.lua
+	$(RM) gen-lua/ThriftTest_ttypes.lua.bak
 
 precross: stubs