diff --git a/overlays/unstable/default.nix b/overlays/unstable/default.nix
index 4ba1183..47184e5 100644
--- a/overlays/unstable/default.nix
+++ b/overlays/unstable/default.nix
@@ -34,9 +34,13 @@ final: prev: {
           channels.unstable.rocmPackages.rocwmma
         ];
 
+        # rocwmma is header-only and ships no CMake config; hipcc/clang
+        # bypass the cc-wrapper, so inject the include path directly.
         cmakeFlags = (prevAttrs.cmakeFlags or [ ]) ++ [
           "-DGGML_HIP_ROCWMMA_FATTN=ON"
           "-DGGML_HIP_GRAPHS=ON"
+          "-DCMAKE_HIP_FLAGS=-I${channels.unstable.rocmPackages.rocwmma}/include"
+          "-DCMAKE_CXX_FLAGS=-I${channels.unstable.rocmPackages.rocwmma}/include"
         ];
       });