diff --git a/gfx/thebes/test/Makefile.in b/gfx/thebes/test/Makefile.in
index 58947dabdfd2..cc46bccdc10f 100644
--- a/gfx/thebes/test/Makefile.in
+++ b/gfx/thebes/test/Makefile.in
@@ -82,6 +82,7 @@ LIBS =  $(HELPER_OBJS) \
 	$(NSPR_LIBS) \
 	$(call EXPAND_MOZLIBNAME,thebes) \
 	$(TK_LIBS) \
+	$(ZLIB_LIBS) \
 	$(NULL)
 
 ifeq ($(MOZ_GFX_TOOLKIT),windows)