--- a/unix/Makefile.in
+++ b/unix/Makefile.in
@@ -869,7 +869,7 @@
 	$(CC) -c $(CC_SWITCHES) $(GENERIC_DIR)/tclCmdIL.c
 
 tclCmdMZ.o: $(GENERIC_DIR)/tclCmdMZ.c
-	$(CC) -c $(CC_SWITCHES) $(GENERIC_DIR)/tclCmdMZ.c
+	$(CC) -c $(CC_SWITCHES) -U_FORTIFY_SOURCE $(GENERIC_DIR)/tclCmdMZ.c
 
 tclDate.o: $(GENERIC_DIR)/tclDate.c
 	$(CC) -c $(CC_SWITCHES) $(GENERIC_DIR)/tclDate.c
