diff --git a/Python/pystate.c b/Python/pystate.c
index 77534fc..d5d98b0 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -569,6 +569,8 @@
 {
     assert(i && t); /* must init with valid states */
     autoTLSkey = PyThread_create_key();
+    if (autoTLSkey == -1)
+        Py_FatalError("Could not allocate TLS entry");
     autoInterpreterState = i;
     assert(PyThread_get_key_value(autoTLSkey) == NULL);
     assert(t->gilstate_counter == 0);
diff --git a/Python/thread_nt.h b/Python/thread_nt.h
index 2fd7098..9de9e0d 100644
--- a/Python/thread_nt.h
+++ b/Python/thread_nt.h
@@ -315,7 +315,10 @@
 int
 PyThread_create_key(void)
 {
-    return (int) TlsAlloc();
+    DWORD result= TlsAlloc();
+    if (result == TLS_OUT_OF_INDEXES)
+        return -1;
+    return (int)result;
 }
 
 void
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index 5e52b39..a529b7a 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -558,3 +558,46 @@
 }
 
 #define THREAD_SET_STACKSIZE(x) _pythread_pthread_set_stacksize(x)
+
+#define Py_HAVE_NATIVE_TLS
+
+int
+PyThread_create_key(void)
+{
+    pthread_key_t key;
+    int fail = pthread_key_create(&key, NULL);
+    return fail ? -1 : key;
+}
+
+void
+PyThread_delete_key(int key)
+{
+    pthread_key_delete(key);
+}
+
+void
+PyThread_delete_key_value(int key)
+{
+    pthread_setspecific(key, NULL);
+}
+
+int
+PyThread_set_key_value(int key, void *value)
+{
+    int fail;
+    void *oldValue = pthread_getspecific(key);
+    if (oldValue != NULL)
+        return 0;
+    fail = pthread_setspecific(key, value);
+    return fail ? -1 : 0;
+}
+
+void *
+PyThread_get_key_value(int key)
+{
+    return pthread_getspecific(key);
+}
+
+void
+PyThread_ReInitTLS(void)
+{}