diff --git a/sched/pthread/pthread_findjoininfo.c b/sched/pthread/pthread_findjoininfo.c
index f977a33642..cf9101ef5e 100644
--- a/sched/pthread/pthread_findjoininfo.c
+++ b/sched/pthread/pthread_findjoininfo.c
@@ -140,7 +140,8 @@ FAR struct join_s *pthread_findjoininfo(FAR struct task_group_s *group,
     {
       FAR struct tcb_s *tcb = nxsched_get_tcb((pthread_t)pid);
 
-      if (tcb != NULL && (tcb->flags & TCB_FLAG_DETACHED) == 0)
+      if (tcb != NULL && (tcb->flags & TCB_FLAG_DETACHED) == 0 &&
+          (tcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_PTHREAD)
         {
           pjoin = pthread_createjoininfo((FAR struct pthread_tcb_s *)tcb);
         }
diff --git a/sched/pthread/pthread_join.c b/sched/pthread/pthread_join.c
index 398e35100d..b864b64e75 100644
--- a/sched/pthread/pthread_join.c
+++ b/sched/pthread/pthread_join.c
@@ -75,6 +75,7 @@ int pthread_join(pthread_t thread, FAR pthread_addr_t *pexit_value)
   FAR struct tcb_s *rtcb = this_task();
   FAR struct task_group_s *group = rtcb->group;
   FAR struct join_s *pjoin;
+  FAR struct tcb_s *tcb;
   int ret;
 
   sinfo("thread=%d group=%p\n", thread, group);
@@ -84,11 +85,18 @@ int pthread_join(pthread_t thread, FAR pthread_addr_t *pexit_value)
 
   enter_cancellation_point();
 
+  tcb = nxsched_get_tcb(thread);
+  if (tcb != NULL && tcb->group != group)
+    {
+      leave_cancellation_point();
+      return EINVAL;
+    }
+
   /* First make sure that this is not an attempt to join to
    * ourself.
    */
 
-  if ((pid_t)thread == gettid())
+  if (tcb == rtcb)
     {
       leave_cancellation_point();
       return EDEADLK;
@@ -114,8 +122,6 @@ int pthread_join(pthread_t thread, FAR pthread_addr_t *pexit_value)
     {
       /* Determine what kind of error to return */
 
-      FAR struct tcb_s *tcb = nxsched_get_tcb((pthread_t)thread);
-
       swarn("WARNING: Could not find thread data\n");
 
       /* Case (1) or (3) -- we can't tell which.  Assume (3) */