diff --git a/src/CHANGELOG b/src/CHANGELOG
index 80390ff65..1f96c9915 100755
--- a/src/CHANGELOG
+++ b/src/CHANGELOG
@@ -15,6 +15,8 @@ ECL 10.1.1:
 
  - PROCESS-JOIN was exported from the wrong package.
 
+ - PROCESS-JOIN would fail when called while a thread was being started.
+
 ;;; Local Variables: ***
 ;;; mode:text ***
 ;;; fill-column:79 ***
diff --git a/src/c/threads.d b/src/c/threads.d
index 478f1b642..c606aa3c1 100644
--- a/src/c/threads.d
+++ b/src/c/threads.d
@@ -141,6 +141,7 @@ thread_entry_point(void *arg)
         cl_object process = (cl_object)arg;
 	cl_env_ptr env;
 
+        process->process.active = 2;
 #ifndef ECL_WINDOWS_THREADS
 	pthread_cleanup_push(thread_cleanup, (void *)process);
 #endif
@@ -434,9 +435,11 @@ mp_process_join(cl_object process)
 {
 	assert_type_process(process);
 	/* We only wait for threads that we have created */
-        if (process->process.active != 1) {
+        if (process->process.active) {
 		cl_object l = process->process.exit_lock;
 		if (!Null(l)) {
+                        while (process->process.active != 1)
+                                cl_sleep(MAKE_FIXNUM(0));
 			l = mp_get_lock(1, l);
 			if (Null(l)) {
 				FEerror("MP:PROCESS-JOIN: Error when "