diff --git a/src/thread/pthread_condattr_setpshared.c b/src/thread/pthread_condattr_setpshared.c
index bece8a269c9b8ccc62498e0d3378946358b1cd5e..51453e0480a822aa88f3797c586d6ceb2e4bb7b3 100644
--- a/src/thread/pthread_condattr_setpshared.c
+++ b/src/thread/pthread_condattr_setpshared.c
@@ -4,6 +4,6 @@ int pthread_condattr_setpshared(pthread_condattr_t *a, int pshared)
 {
 	if (pshared > 1U) return EINVAL;
 	a->__attr &= 0x7fffffff;
-	a->__attr |= pshared<<31;
+	a->__attr |= (unsigned)pshared<<31;
 	return 0;
 }