Index: src/OFObject.m
==================================================================
--- src/OFObject.m
+++ src/OFObject.m
@@ -140,11 +140,11 @@
 of_method_not_found_stret(void *st, id obj, SEL sel)
 {
 	of_method_not_found(obj, sel);
 }
 
-#ifndef HAVE_OBJC_ENUMERATIONMUTATION
+#if !defined(OF_OBJFW_RUNTIME) && !defined(HAVE_OBJC_ENUMERATIONMUTATION)
 void
 objc_enumerationMutation(id object)
 {
 	enumerationMutationHandler(object);
 }
@@ -226,11 +226,11 @@
 	objc_setForwardHandler((void*)&of_forward, (void*)&of_forward_stret);
 #else
 	objc_setForwardHandler((IMP)&of_forward, (IMP)&of_forward_stret);
 #endif
 
-#ifdef HAVE_OBJC_ENUMERATIONMUTATION
+#if defined(OF_OBJFW_RUNTIME) || defined(HAVE_OBJC_ENUMERATIONMUTATION)
 	objc_setEnumerationMutationHandler(enumerationMutationHandler);
 #endif
 
 	of_hash_seed = 0;
 	while (of_hash_seed == 0) {

Index: src/runtime/Makefile
==================================================================
--- src/runtime/Makefile
+++ src/runtime/Makefile
@@ -11,10 +11,11 @@
        dtable.m			\
        exception.m		\
        hashtable.m		\
        init.m			\
        lookup.m			\
+       misc.m			\
        property.m		\
        protocol.m		\
        selector.m		\
        sparsearray.m		\
        static-instances.m	\

ADDED   src/runtime/misc.m
Index: src/runtime/misc.m
==================================================================
--- /dev/null
+++ src/runtime/misc.m
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016
+ *   Jonathan Schleifer <js@heap.zone>
+ *
+ * All rights reserved.
+ *
+ * This file is part of ObjFW. It may be distributed under the terms of the
+ * Q Public License 1.0, which can be found in the file LICENSE.QPL included in
+ * the packaging of this file.
+ *
+ * Alternatively, it may be distributed under the terms of the GNU General
+ * Public License, either version 2 or 3, which can be found in the file
+ * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
+ * file.
+ */
+
+#include "config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "runtime.h"
+#include "runtime-private.h"
+
+static void (*enumeration_mutation_handler)(id) = NULL;
+
+void
+objc_enumerationMutation(id obj)
+{
+	if (enumeration_mutation_handler != NULL)
+		enumeration_mutation_handler(obj);
+	else
+		OBJC_ERROR("Object was mutated during enumeration!");
+}
+
+void
+objc_setEnumerationMutationHandler(void (*handler)(id))
+{
+	enumeration_mutation_handler = handler;
+}

Index: src/runtime/runtime.h
==================================================================
--- src/runtime/runtime.h
+++ src/runtime/runtime.h
@@ -237,10 +237,12 @@
 /* Used by the compiler, but can be called manually. */
 extern IMP objc_msg_lookup(id, SEL);
 extern IMP objc_msg_lookup_stret(id, SEL);
 extern IMP objc_msg_lookup_super(struct objc_super*, SEL);
 extern IMP objc_msg_lookup_super_stret(struct objc_super*, SEL);
+extern void objc_enumerationMutation(id);
+extern void objc_setEnumerationMutationHandler(void (*handler)(id));
 #ifdef __cplusplus
 }
 #endif
 
 #undef OBJC_UNSAFE_UNRETAINED