diff --git a/tests/libtest/Makefile.inc b/tests/libtest/Makefile.inc
index e0ebcb4c7a..3cbc45aad8 100644
--- a/tests/libtest/Makefile.inc
+++ b/tests/libtest/Makefile.inc
@@ -189,7 +189,7 @@ lib599_SOURCES = lib599.c $(SUPPORTFILES)
 
 lib1500_SOURCES = lib1500.c $(SUPPORTFILES) $(TESTUTIL)
 
-lib1501_SOURCES = lib1501.c $(SUPPORTFILES) $(TESTUTIL)
+lib1501_SOURCES = lib1501.c $(SUPPORTFILES) $(TESTUTIL) $(WARNLESS)
 
 libauthretry_SOURCES = libauthretry.c $(SUPPORTFILES)