diff --git a/pkgs/development/libraries/science/math/openblas/default.nix b/pkgs/development/libraries/science/math/openblas/default.nix
index 67d95f97e074..0597cbae77ae 100644
--- a/pkgs/development/libraries/science/math/openblas/default.nix
+++ b/pkgs/development/libraries/science/math/openblas/default.nix
@@ -14,6 +14,8 @@ let local = config.openblas.preferLocalBuild or false;
         "DYNAMIC_ARCH=1"
         "NUM_THREADS=64"
         "BINARY=${binary}"
+        "USE_OPENMP=1"
+        "NUM_THREADS=64"
       ];
     localFlags = config.openblas.flags or
       optionals (hasAttr "target" config.openblas) [ "TARGET=${config.openblas.target}" ];