Index: src/platform/amiga/thread.m
==================================================================
--- src/platform/amiga/thread.m
+++ src/platform/amiga/thread.m
@@ -27,11 +27,13 @@
 
 #include <dos/dostags.h>
 #include <proto/dos.h>
 #include <proto/exec.h>
 
+#ifndef OF_MORPHOS
 extern void of_tlskey_thread_exited(void);
+#endif
 static of_tlskey_t threadKey;
 
 OF_CONSTRUCTOR()
 {
 	OF_ENSURE(of_tlskey_new(&threadKey));
@@ -49,11 +51,13 @@
 
 	ObtainSemaphore(&thread->semaphore);
 	@try {
 		thread->done = true;
 
+#ifndef OF_MORPHOS
 		of_tlskey_thread_exited();
+#endif
 
 		if (thread->detached)
 			detached = true;
 		else if (thread->joinTask != NULL)
 			Signal(thread->joinTask, (1ul << thread->joinSigBit));

ADDED   src/platform/morphos/tlskey.m
Index: src/platform/morphos/tlskey.m
==================================================================
--- src/platform/morphos/tlskey.m
+++ src/platform/morphos/tlskey.m
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017,
+ *               2018, 2019, 2020
+ *   Jonathan Schleifer <js@nil.im>
+ *
+ * All rights reserved.
+ *
+ * This file is part of ObjFW. It may be distributed under the terms of the
+ * Q Public License 1.0, which can be found in the file LICENSE.QPL included in
+ * the packaging of this file.
+ *
+ * Alternatively, it may be distributed under the terms of the GNU General
+ * Public License, either version 2 or 3, which can be found in the file
+ * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
+ * file.
+ */
+
+#include "config.h"
+
+#import "tlskey.h"
+
+bool
+of_tlskey_new(of_tlskey_t *key)
+{
+	return ((*key = TLSAllocA(NULL)) != TLS_INVALID_INDEX);
+}
+
+bool
+of_tlskey_free(of_tlskey_t key)
+{
+	return TLSFree(key);
+}

Index: src/tlskey.h
==================================================================
--- src/tlskey.h
+++ src/tlskey.h
@@ -30,10 +30,13 @@
 # include <pthread.h>
 typedef pthread_key_t of_tlskey_t;
 #elif defined(OF_WINDOWS)
 # include <windows.h>
 typedef DWORD of_tlskey_t;
+#elif defined(OF_MORPHOS)
+# include <proto/exec.h>
+typedef ULONG of_tlskey_t;
 #elif defined(OF_AMIGAOS)
 typedef struct of_tlskey {
 	struct objc_hashtable *table;
 	struct of_tlskey *next, *previous;
 } *of_tlskey_t;
@@ -72,10 +75,22 @@
 static OF_INLINE bool
 of_tlskey_set(of_tlskey_t key, void *ptr)
 {
 	return TlsSetValue(key, ptr);
 }
+#elif defined(OF_MORPHOS)
+static OF_INLINE void *
+of_tlskey_get(of_tlskey_t key)
+{
+	return (void *)TLSGetValue(key);
+}
+
+static OF_INLINE bool
+of_tlskey_set(of_tlskey_t key, void *ptr)
+{
+	return TLSSetValue(key, (APTR)ptr);
+}
 #elif defined(OF_AMIGAOS)
 /* Those are too big too inline. */
 # ifdef __cplusplus
 extern "C" {
 # endif

Index: src/tlskey.m
==================================================================
--- src/tlskey.m
+++ src/tlskey.m
@@ -21,8 +21,10 @@
 
 #if defined(OF_HAVE_PTHREADS)
 # include "platform/posix/tlskey.m"
 #elif defined(OF_WINDOWS)
 # include "platform/windows/tlskey.m"
+#elif defined(OF_MORPHOS)
+# include "platform/morphos/tlskey.m"
 #elif defined(OF_AMIGAOS)
 # include "platform/amiga/tlskey.m"
 #endif