Index: src/OFEmbeddedIRIHandler.m
==================================================================
--- src/OFEmbeddedIRIHandler.m
+++ src/OFEmbeddedIRIHandler.m
@@ -70,15 +70,17 @@
 	OFEnsure(OFPlainMutexUnlock(&mutex) == 0);
 #endif
 }
 
 @implementation OFEmbeddedIRIHandler
+#ifdef OF_HAVE_THREADS
 + (void)initialize
 {
 	if (self == [OFEmbeddedIRIHandler class])
 		OFOnce(&mutexOnceControl, initMutex);
 }
+#endif
 
 - (OFStream *)openItemAtIRI: (OFIRI *)IRI mode: (OFString *)mode
 {
 	OFString *path;