diff --git a/src/testdir/Make_mvc.mak b/src/testdir/Make_mvc.mak
index bb38e25..bbfd8f0 100644
--- a/src/testdir/Make_mvc.mak
+++ b/src/testdir/Make_mvc.mak
@@ -151,8 +151,9 @@
 	$(VIMPROG) -u gui_preinit.vim -U gui_init.vim $(NO_PLUGINS) -S runtest.vim $*.vim
 	@del vimcmd
 
-opt_test.vim: ../optiondefs.h gen_opt_test.vim
-	$(VIMPROG) -e -s -u NONE $(COMMON_ARGS) --nofork -S gen_opt_test.vim ../optiondefs.h
+opt_test.vim: gen_opt_test.vim ../optiondefs.h
+	$(VIMPROG) -e -s -u NONE $(COMMON_ARGS) --nofork -S $**
+	@if exist test.log ( type test.log & exit /b 1 )
 
 test_bench_regexp.res: test_bench_regexp.vim
 	-if exist benchmark.out del benchmark.out