1 files changed, 1 insertions, 1 deletions
diff --git a/thread.c b/thread.c
index 9c7fcee05f..90cb1c226e 100644
--- a/thread.c
+++ b/thread.c
@@ -3608,7 +3608,7 @@ rb_thread_priority_set(VALUE thread, VALUE prio)
     else if (priority < RUBY_THREAD_PRIORITY_MIN) {
 	priority = RUBY_THREAD_PRIORITY_MIN;
     }
-    target_th->priority = priority;
+    target_th->priority = (int8_t)priority;
 #endif
     return INT2NUM(target_th->priority);
 }