diff --git a/lib/Makefile.m32 b/lib/Makefile.m32
index 628140d16..842c29b36 100644
--- a/lib/Makefile.m32
+++ b/lib/Makefile.m32
@@ -27,7 +27,7 @@ ifdef SSL
 endif
 ifdef ZLIB
 	INCLUDES += -I"$(ZLIB_PATH)"
-	CFLAGS += -DHAVE_ZLIB -DHAVE_ZLIB_H
+	CFLAGS += -DHAVE_LIBZ -DHAVE_ZLIB_H
 	DLL_LIBS += -L$(ZLIB_PATH) -lz
 endif
 COMPILE = $(CC) $(INCLUDES) $(CFLAGS)