Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -499,11 +499,11 @@
 		@end
 
 		void *_OFConstantStringClassReference;
 	], [
 		OFConstantString *test = @"";
-		test++; /* Get rid of unused variable warning */
+		(void)test; /* Get rid of unused variable warning */
 	], [
 		AC_MSG_RESULT(no)
 	], [
 		AC_MSG_RESULT([yes, adding -Wno-unused-variable])
 		OBJCFLAGS="$OBJCFLAGS -Wno-unused-variable"
@@ -521,11 +521,11 @@
 		static struct {
 			struct objc_class *isa;
 		} object;
 	], [
 		OFObject *test = (OFObject*)&object;
-		test++; /* Get rid of unused variable warning */
+		(void)test; /* Get rid of unused variable warning */
 	], [
 		AC_MSG_RESULT(no)
 	], [
 		AC_MSG_RESULT(yes)
 		OBJCFLAGS="$OBJCFLAGS -Wno-strict-aliasing"