diff --git a/pkgs/development/interpreters/cling/default.nix b/pkgs/development/interpreters/cling/default.nix
index 8f80d2f4ee68..dbc2751e7899 100644
--- a/pkgs/development/interpreters/cling/default.nix
+++ b/pkgs/development/interpreters/cling/default.nix
@@ -1,5 +1,5 @@
 { lib, stdenv
-, python
+, python3
 , libffi
 , git
 , cmake
@@ -38,9 +38,11 @@ let
       chmod -R a+w ./tools/cling
     '';
 
-    nativeBuildInputs = [ python git cmake ];
+    nativeBuildInputs = [ python3 git cmake ];
     buildInputs = [ libffi llvmPackages_5.llvm zlib ];
 
+    strictDeps = true;
+
     cmakeFlags = [
       "-DLLVM_TARGETS_TO_BUILD=host;NVPTX"
       "-DLLVM_ENABLE_RTTI=ON"