diff --git a/src/alloc.c b/src/alloc.c
index e979f3631ee..93ea286cfb8 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -6406,7 +6406,7 @@ mark_object (Lisp_Object arg)
 
 #ifdef GC_CHECK_MARKED_OBJECTS
 	m = mem_find (po);
-	if (m == MEM_NIL && !SUBRP (obj) && !THREADP (obj))
+	if (m == MEM_NIL && !SUBRP (obj) && !primary_thread_p (po))
 	  emacs_abort ();
 #endif /* GC_CHECK_MARKED_OBJECTS */
 
@@ -6418,7 +6418,7 @@ mark_object (Lisp_Object arg)
 
 	if (pvectype != PVEC_SUBR
 	    && pvectype != PVEC_BUFFER
-	    && pvectype != PVEC_THREAD)
+	    && !primary_thread_p (po))
 	  CHECK_LIVE (live_vector_p);
 
 	switch (pvectype)
diff --git a/src/thread.c b/src/thread.c
index bf2cf1b06c8..6966df31d37 100644
--- a/src/thread.c
+++ b/src/thread.c
@@ -950,6 +950,12 @@ init_primary_thread (void)
   primary_thread.event_object = Qnil;
 }
 
+bool
+primary_thread_p (void *ptr)
+{
+  return (ptr == &primary_thread) ? true : false;
+}
+
 void
 init_threads_once (void)
 {
diff --git a/src/thread.h b/src/thread.h
index 7dee67d6595..0090652b358 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -236,6 +236,7 @@ extern void maybe_reacquire_global_lock (void);
 extern void init_threads_once (void);
 extern void init_threads (void);
 extern void syms_of_threads (void);
+extern bool primary_thread_p (void *);
 
 typedef int select_func (int, fd_set *, fd_set *, fd_set *,
 			 const struct timespec *, const sigset_t *);