diff --git a/src/internal/ptycon_bridge_impl.h b/src/internal/ptycon_bridge_impl.h
index 49c1cad..621a5c6 100644
--- a/src/internal/ptycon_bridge_impl.h
+++ b/src/internal/ptycon_bridge_impl.h
@@ -32,8 +32,8 @@ struct ptyc_term_input {
 };
 
 struct ptyc_vkcode {
-	const unsigned char const *	mbstr;
-	uint16_t			mblen;
+	const unsigned char * const	mbstr;
+	const uint16_t			mblen;
 };
 
 struct ptyc_term_ctx;