1 files changed, 2 insertions, 1 deletions
diff --git a/io.c b/io.c
index 369fe9d838..a051ffad38 100644
--- a/io.c
+++ b/io.c
@@ -1001,7 +1001,8 @@ pipe_open(pname, mode)
 	break;
 
       default:			/* parent */
-	{
+	if (pid > 0) rb_sys_fail(0);
+	else {
 	    NEWOBJ(port, struct RFile);
 	    OBJSETUP(port, cIO, T_FILE);
 	    MakeOpenFile(port, fptr);