tests: Build all tests with strict prototypes.
diff --git a/dlls/Maketest.rules.in b/dlls/Maketest.rules.in
index aff002c..95f5c2b 100644
--- a/dlls/Maketest.rules.in
+++ b/dlls/Maketest.rules.in
@@ -10,7 +10,7 @@
 #
 
 DLLFLAGS     = @DLLFLAGS@
-DEFS         = $(EXTRADEFS)
+DEFS         = -DWINE_STRICT_PROTOTYPES $(EXTRADEFS)
 
 MODULE       = $(TESTDLL:%.dll=%)_test.exe
 TESTRESULTS  = $(CTESTS:.c=.ok)