diff --git a/exec/coroipcs.c b/exec/coroipcs.c
index 3e8eb2d2..03e580c5 100644
--- a/exec/coroipcs.c
+++ b/exec/coroipcs.c
@@ -183,7 +183,7 @@ retry_semop:
 		goto retry_semop;
 	}
 #else
-	sop.sem_num = 1;
+	sop.sem_num = 0;
 	sop.sem_op = 1;
 	sop.sem_flg = 0;