diff --git a/pkgs/development/tools/build-managers/cmake/setup-hook.sh b/pkgs/development/tools/build-managers/cmake/setup-hook.sh
index 802c7343a854..32e0b76f608a 100755
--- a/pkgs/development/tools/build-managers/cmake/setup-hook.sh
+++ b/pkgs/development/tools/build-managers/cmake/setup-hook.sh
@@ -37,7 +37,8 @@ cmakeConfigurePhase() {
     fi
 
     # Avoid cmake resetting the rpath of binaries, on make install
-    cmakeFlags="-DCMAKE_SKIP_BUILD_RPATH=ON $cmakeFlags"
+    # And build always Release, to ensure optimisation flags
+    cmakeFlags="-DCMAKE_BUILD_TYPE=Release -DCMAKE_SKIP_BUILD_RPATH=ON $cmakeFlags"
 
     echo "cmake flags: $cmakeFlags ${cmakeFlagsArray[@]}"