diff --git a/pkgs/development/libraries/opencv/3.x.nix b/pkgs/development/libraries/opencv/3.x.nix
index f6ec1be0949..187b6df39b2 100644
--- a/pkgs/development/libraries/opencv/3.x.nix
+++ b/pkgs/development/libraries/opencv/3.x.nix
@@ -62,7 +62,7 @@ stdenv.mkDerivation rec {
 
   buildInputs =
        [ zlib ]
-    ++ lib.optionals enablePython [ pythonPackages.python pythonPackages.numpy ]
+    ++ lib.optional enablePython pythonPackages.python
     ++ lib.optional enableGtk2 gtk2
     ++ lib.optional enableGtk3 gtk3
     ++ lib.optional enableJPEG libjpeg
@@ -76,6 +76,8 @@ stdenv.mkDerivation rec {
     ++ lib.optional enableEigen eigen
     ;
 
+  propagatedBuildInputs = lib.optional enablePython pythonPackages.numpy;
+
   nativeBuildInputs = [ cmake pkgconfig unzip ];
 
   NIX_CFLAGS_COMPILE = lib.optional enableEXR "-I${ilmbase}/include/OpenEXR";
diff --git a/pkgs/development/libraries/opencv/default.nix b/pkgs/development/libraries/opencv/default.nix
index 82d597a17c9..70ea306ae80 100644
--- a/pkgs/development/libraries/opencv/default.nix
+++ b/pkgs/development/libraries/opencv/default.nix
@@ -30,6 +30,7 @@ stdenv.mkDerivation rec {
 
   buildInputs =
        [ zlib ]
+    ++ lib.optional enablePython pythonPackages.python
     ++ lib.optional enableGtk2 gtk2
     ++ lib.optional enableJPEG libjpeg
     ++ lib.optional enablePNG libpng
@@ -41,6 +42,8 @@ stdenv.mkDerivation rec {
     ++ lib.optional enableEigen eigen
     ;
 
+  propagatedBuildInputs = lib.optional enablePython pythonPackages.numpy;
+
   nativeBuildInputs = [ cmake pkgconfig unzip ];
 
   NIX_CFLAGS_COMPILE = lib.optional enableEXR "-I${ilmbase}/include/OpenEXR";