diff --git a/contrib/rserv/rserv.c b/contrib/rserv/rserv.c
index be957a3454981fe8a6b9291387ea90bd1f845976..517289dc1cc544dca6b5fe2e8d6ebb35565c9d02 100644
--- a/contrib/rserv/rserv.c
+++ b/contrib/rserv/rserv.c
@@ -102,7 +102,7 @@ _rserv_log_()
 
 	if (keynum == ObjectIdAttributeNumber)
 	{
-		snprintf(oidbuf, "%u", sizeof(oidbuf), HeapTupleGetOid(tuple));
+		snprintf(oidbuf, sizeof(oidbuf), "%u", HeapTupleGetOid(tuple));
 		key = oidbuf;
 	}
 	else