Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -659,10 +659,11 @@
 		AC_SUBST(RUNTIME_AUTORELEASE_M, "runtime/autorelease.m")
 	])
 	AC_CHECK_FUNC(objc_constructInstance, [], [
 		AC_SUBST(RUNTIME_INSTANCE_M, "runtime/instance.m")
 	])
+	AC_CHECK_FUNCS(objc_setAssociatedObject)
 
 	OBJCFLAGS="$old_OBJCFLAGS"
 	;;
 esac
 

Index: src/OFDNSResolver.m
==================================================================
--- src/OFDNSResolver.m
+++ src/OFDNSResolver.m
@@ -876,12 +876,12 @@
 	removeList = [OFMutableArray arrayWithCapacity: _cache.count];
 
 	for (OFDNSQuery *query in _cache) {
 		OFPair OF_GENERIC(OFDate *, OFDNSResponse *) *entry =
 		    [_cache objectForKey: query];
-		uint32_t age =
-		    (uint32_t)now - [entry.firstObject timeIntervalSince1970];
+		uint32_t age = (uint32_t)now -
+		    (uint32_t)[entry.firstObject timeIntervalSince1970];
 		OFDNSResponse *response = entry.secondObject;
 
 		if (containsExpiredRecord(response.answerRecords, age) ||
 		    containsExpiredRecord(response.authorityRecords, age) ||
 		    containsExpiredRecord(response.additionalRecords, age))

Index: src/runtime/instance.m
==================================================================
--- src/runtime/instance.m
+++ src/runtime/instance.m
@@ -100,9 +100,11 @@
 			last = destruct;
 		} else
 			break;
 	}
 
+#if defined(OF_OBJFW_RUNTIME) || defined(HAVE_OBJC_SETASSOCIATEDOBJECT)
 	objc_removeAssociatedObjects(object);
+#endif
 
 	return object;
 }

Index: src/test/OTAppDelegate.m
==================================================================
--- src/test/OTAppDelegate.m
+++ src/test/OTAppDelegate.m
@@ -147,36 +147,43 @@
 #endif
 }
 
 - (OFMutableSet OF_GENERIC(Class) *)testClasses
 {
-	Class *classes = objc_copyClassList(NULL);
+	Class *classes;
+	int classesCount;
 	OFMutableSet *testClasses;
 
-	if (classes == NULL)
+	classesCount = objc_getClassList(NULL, 0);
+	if (classesCount < 1)
 		return nil;
 
+	classes = OFAllocMemory(classesCount, sizeof(Class));
 	@try {
+		if ((int)objc_getClassList(classes, classesCount) !=
+		    classesCount)
+			return nil;
+
 		testClasses = [OFMutableSet set];
 
-		for (Class *iter = classes; *iter != Nil; iter++) {
+		for (int i = 0; i < classesCount; i++) {
 			/*
 			 * Make sure the class is initialized.
 			 * Required for the ObjFW runtime, as otherwise
 			 * class_getSuperclass() crashes.
 			 */
 #ifdef OF_OBJFW_RUNTIME
-			[*iter class];
+			[classes[i] class];
 #endif
 
 			/*
 			 * Don't use +[isSubclassOfClass:], as the Apple runtime
 			 * can return (presumably internal?) classes that don't
 			 * implement it, resulting in a crash.
 			 */
-			if (isSubclassOfClass(*iter, [OTTestCase class]))
-				[testClasses addObject: *iter];
+			if (isSubclassOfClass(classes[i], [OTTestCase class]))
+				[testClasses addObject: classes[i]];
 		}
 	} @finally {
 		OFFreeMemory(classes);
 	}
 

Index: tests/RuntimeTests.m
==================================================================
--- tests/RuntimeTests.m
+++ tests/RuntimeTests.m
@@ -84,10 +84,11 @@
 	_test.bar = string;
 	OTAssertEqual(_test.bar, string);
 	OTAssertEqual(string.retainCount, 3);
 }
 
+#if defined(OF_OBJFW_RUNTIME) || defined(HAVE_OBJC_SETASSOCIATEDOBJECT)
 - (void)testAssociatedObjects
 {
 	objc_setAssociatedObject(self, testKey, _test, OBJC_ASSOCIATION_ASSIGN);
 	OTAssertEqual(_test.retainCount, 1);
 
@@ -108,10 +109,11 @@
 	OTAssertEqual(_test.retainCount, 3);
 
 	objc_removeAssociatedObjects(self);
 	OTAssertEqual(_test.retainCount, 2);
 }
+#endif
 
 #ifdef OF_OBJFW_RUNTIME
 - (void)testTaggedPointers
 {
 	int classID;