1 files changed, 2 insertions, 1 deletions
diff --git a/process.c b/process.c
index 9a19d0145e..1fd43e30b3 100644
--- a/process.c
+++ b/process.c
@@ -891,8 +891,9 @@ proc_getpriority(obj, which, who)
     iwhich = NUM2INT(which);
     iwho   = NUM2INT(who);
 
+    errno = 0;
     prio = getpriority(iwhich, iwho);
-    if (prio < 0) rb_sys_fail(0);
+    if (errno) rb_sys_fail(0);
     return INT2FIX(prio);
 #else
     rb_notimplement();