diff --git a/src/kamailio/core.lua b/src/kamailio/core.lua
index 32cdad1..e331a75 100644
--- a/src/kamailio/core.lua
+++ b/src/kamailio/core.lua
@@ -13,7 +13,11 @@ function core.set_branch_flag(flag)
 end
 
 function core.is_flag_set(flag)
-  return KSR.isflagset(FLT_NATS)
+  return KSR.isflagset(flag)
 end
 
-return core
\ No newline at end of file
+function core.is_branch_flag_set(flag)
+    return KSR.isbflagset(flag)
+end
+
+return core