Index: src/OFURLHandler.h
==================================================================
--- src/OFURLHandler.h
+++ src/OFURLHandler.h
@@ -56,11 +56,11 @@
 /**
  * @brief Returns the handler for the specified URL.
  *
  * @return The handler for the specified URL.
  */
-+ (nullable OF_KINDOF(OFURLHandler *))handlerForURL: (OFURL *)URL;
++ (OF_KINDOF(OFURLHandler *))handlerForURL: (OFURL *)URL;
 
 - (instancetype)init OF_UNAVAILABLE;
 
 /**
  * @brief Initializes the handler for the specified scheme.

Index: src/OFURLHandler.m
==================================================================
--- src/OFURLHandler.m
+++ src/OFURLHandler.m
@@ -29,10 +29,12 @@
 # import "OFFileURLHandler.h"
 #endif
 #if defined(OF_HAVE_SOCKETS) && defined(OF_HAVE_THREADS)
 # import "OFHTTPURLHandler.h"
 #endif
+
+#import "OFUnsupportedProtocolException.h"
 
 static OFMutableDictionary OF_GENERIC(OFString *, OFURLHandler *) *handlers;
 #ifdef OF_HAVE_THREADS
 static OFMutex *mutex;
 
@@ -107,10 +109,13 @@
 	} @finally {
 		[mutex unlock];
 	}
 #endif
 
+	if (handler == nil)
+		@throw [OFUnsupportedProtocolException exceptionWithURL: URL];
+
 	return handler;
 }
 
 - (instancetype)init
 {