diff --git a/include/cute/atom/mma_atom.hpp b/include/cute/atom/mma_atom.hpp
index e4499a10..ae606153 100644
--- a/include/cute/atom/mma_atom.hpp
+++ b/include/cute/atom/mma_atom.hpp
@@ -391,6 +391,8 @@ struct TiledMMA : MMA_Atom
     } else {
       return cute::max(core_size, perm_size);
     }
+
+    CUTE_GCC_UNREACHABLE;
   }
 
   CUTE_HOST_DEVICE constexpr