diff --git a/src/ruc/meta/core.h b/src/ruc/meta/core.h
index 03920cc..6918695 100644
--- a/src/ruc/meta/core.h
+++ b/src/ruc/meta/core.h
@@ -7,3 +7,6 @@
 #pragma once
 
 #define BIT(x) (1 << x)
+
+#define CONCAT_IMPL(a, b) a##b
+#define CONCAT(a, b) CONCAT_IMPL(a, b)