diff --git a/pkgs/development/python-modules/numpy/default.nix b/pkgs/development/python-modules/numpy/default.nix
index af8815dbfb1..c66650c0abf 100644
--- a/pkgs/development/python-modules/numpy/default.nix
+++ b/pkgs/development/python-modules/numpy/default.nix
@@ -11,7 +11,8 @@ buildPythonPackage rec {
   };
 
   disabled = isPyPy;
-  buildInputs = [ gfortran pytest blas ];
+  nativeBuildInputs = [ gfortran pytest ];
+  buildInputs = [ blas ];
 
   patches = lib.optionals (python.hasDistutilsCxxPatch or false) [
     # We patch cpython/distutils to fix https://bugs.python.org/issue1222585
diff --git a/pkgs/development/python-modules/scipy/default.nix b/pkgs/development/python-modules/scipy/default.nix
index 140e8cc80b4..5fdffedc6f2 100644
--- a/pkgs/development/python-modules/scipy/default.nix
+++ b/pkgs/development/python-modules/scipy/default.nix
@@ -10,7 +10,8 @@ buildPythonPackage rec {
   };
 
   checkInputs = [ nose pytest ];
-  buildInputs = [ gfortran numpy.blas ];
+  nativeBuildInputs = [ gfortran ];
+  buildInputs = [ numpy.blas ];
   propagatedBuildInputs = [ numpy ];
 
   # Remove tests because of broken wrapper