Index: src/test/OTAppDelegate.m
==================================================================
--- src/test/OTAppDelegate.m
+++ src/test/OTAppDelegate.m
@@ -25,10 +25,20 @@
 #import "OTTestCase.h"
 
 #import "OTAssertionFailedException.h"
 
 OF_APPLICATION_DELEGATE(OTAppDelegate)
+
+static bool
+isSubclassOfClass(Class class, Class superclass)
+{
+	for (Class iter = class; iter != Nil; iter = class_getSuperclass(iter))
+		if (iter == superclass)
+			return true;
+
+	return false;
+}
 
 @implementation OTAppDelegate
 - (OFSet OF_GENERIC(Class) *)testClasses
 {
 	Class *classes = objc_copyClassList(NULL);
@@ -39,11 +49,11 @@
 
 	@try {
 		testClasses = [OFMutableSet set];
 
 		for (Class *iter = classes; *iter != Nil; iter++)
-			if ([*iter isSubclassOfClass: [OTTestCase class]])
+			if (isSubclassOfClass(*iter, [OTTestCase class]))
 				[testClasses addObject: *iter];
 	} @finally {
 		OFFreeMemory(classes);
 	}