@@ -29,12 +29,21 @@
 AX_CHECK_COMPILER_FLAGS(-fno-common, [OBJCFLAGS="$OBJCFLAGS -fno-common"])
 AX_CHECK_COMPILER_FLAGS(-fno-constant-cfstrings, [
 	OBJCFLAGS="$OBJCFLAGS -fno-constant-cfstrings"
 	AC_SUBST(NO_CONST_CFSTRINGS, "-fno-constant-cfstrings")
 ])
-AX_CHECK_COMPILER_FLAGS(-Wshorten-64-to-32,
-	[OBJCFLAGS="$OBJCFLAGS -Wshorten-64-to-32"])
+AX_CHECK_COMPILER_FLAGS(-Wshorten-64-to-32, [
+	old_OBJCFLAGS="$OBJCFLAGS"
+	OBJCFLAGS="$OBJCFLAGS -Wshorten-64-to-32 -Werror"
+	AC_TRY_COMPILE([
+		#import <objc/objc-api.h>
+	], [], [
+		OBJCFLAGS="$old_OBJCFLAGS -Wshorten-64-to-32"
+	], [
+		OBJCFLAGS="$old_OBJCFLAGS"
+	])
+])
 AX_CHECK_COMPILER_FLAGS(-Wsemicolon-before-method-body,
 	[OBJCFLAGS="$OBJCFLAGS -Wsemicolon-before-method-body"])
 
 AC_MSG_CHECKING(whether Objective C compiler supports fast enumeration)
 AC_TRY_COMPILE([