Index: src/OFObject.h
==================================================================
--- src/OFObject.h
+++ src/OFObject.h
@@ -405,11 +405,12 @@
  * All methods from the superclasses of the specified class will also be added.
  *
  * If the specified class is a superclass of the receiving class, nothing is
  * done.
  *
- * The specified class may not use instance variables and has to use accessors.
+ * The methods which will be added from the specified class are not allowed to
+ * use super or access instance variables, instead they have to use accessors.
  *
  * \param class The class from which the instance methods should be inherited
  */
 + (void)inheritMethodsFromClass: (Class)class;
 

Index: src/OFObject.m
==================================================================
--- src/OFObject.m
+++ src/OFObject.m
@@ -455,10 +455,42 @@
 	 withTypeEncoding: (const char*)typeEncoding
 	   implementation: (IMP)implementation
 {
 #if defined(OF_APPLE_RUNTIME) || defined(OF_GNU_RUNTIME)
 	return class_addMethod(self, selector, implementation, typeEncoding);
+#elif defined(OF_OLD_GNU_RUNTIME)
+	MethodList_t methodList;
+
+	for (methodList = ((Class)self)->methods; methodList != NULL;
+	    methodList = methodList->method_next) {
+		int i;
+
+		for (i = 0; i < methodList->method_count; i++)
+			if (sel_eq(methodList->method_list[i].method_name,
+			    selector))
+				return NO;
+	}
+
+	if ((methodList = malloc(sizeof(*methodList))) == NULL)
+		@throw [OFOutOfMemoryException
+		    newWithClass: self
+		   requestedSize: sizeof(*methodList)];
+
+	methodList->method_next = ((Class)self)->methods;
+	methodList->method_count = 1;
+
+	methodList->method_list[0].method_name = selector;
+	methodList->method_list[0].method_types = typeEncoding;
+	methodList->method_list[0].method_imp = implementation;
+
+	((Class)self)->methods = methodList;
+
+	/* Update the dtable */
+	sarray_at_put_safe(((Class)self)->dtable,
+	    (sidx)selector->sel_id, implementation);
+
+	return YES;
 #else
 	@throw [OFNotImplementedException newWithClass: self
 					      selector: _cmd];
 #endif
 }
@@ -468,10 +500,42 @@
 	implementation: (IMP)implementation
 {
 #if defined(OF_APPLE_RUNTIME) || defined(OF_GNU_RUNTIME)
 	return class_addMethod(((OFObject*)self)->isa, selector, implementation,
 	    typeEncoding);
+#elif defined(OF_OLD_GNU_RUNTIME)
+	MethodList_t methodList;
+
+	for (methodList = ((Class)self->class_pointer)->methods;
+	    methodList != NULL; methodList = methodList->method_next) {
+		int i;
+
+		for (i = 0; i < methodList->method_count; i++)
+			if (sel_eq(methodList->method_list[i].method_name,
+			    selector))
+				return NO;
+	}
+
+	if ((methodList = malloc(sizeof(*methodList))) == NULL)
+		@throw [OFOutOfMemoryException
+		    newWithClass: self
+		   requestedSize: sizeof(*methodList)];
+
+	methodList->method_next = ((Class)self->class_pointer)->methods;
+	methodList->method_count = 1;
+
+	methodList->method_list[0].method_name = selector;
+	methodList->method_list[0].method_types = typeEncoding;
+	methodList->method_list[0].method_imp = implementation;
+
+	((Class)self->class_pointer)->methods = methodList;
+
+	/* Update the dtable */
+	sarray_at_put_safe(((Class)self->class_pointer)->dtable,
+	    (sidx)selector->sel_id, implementation);
+
+	return YES;
 #else
 	@throw [OFNotImplementedException newWithClass: self
 					      selector: _cmd];
 #endif
 }