Index: src/OFThread.m
==================================================================
--- src/OFThread.m
+++ src/OFThread.m
@@ -313,10 +313,13 @@
 
 + (void)terminateWithObject: (id)object
 {
 	OFThread *thread = of_tlskey_get(threadSelfKey);
 
+	if (thread == mainThread)
+		@throw [OFInvalidArgumentException exception];
+
 	OF_ENSURE(thread != nil);
 
 	thread->_returnValue = [object retain];
 	longjmp(thread->_exitEnv, 1);