diff --git a/pkgs/development/libraries/crypto++/default.nix b/pkgs/development/libraries/crypto++/default.nix
index a2cfcc45a4ce..f1c5db1caf10 100644
--- a/pkgs/development/libraries/crypto++/default.nix
+++ b/pkgs/development/libraries/crypto++/default.nix
@@ -9,13 +9,13 @@ stdenv.mkDerivation rec {
   };
 
   patches = [ ./pic.patch ]
-    ++ stdenv.lib.optional (builtins.currentSystem != "i686-cygwin") ./dll.patch;
+    ++ stdenv.lib.optional (stdenv.system != "i686-cygwin") ./dll.patch;
 
 
   buildInputs = [ unzip ]
 
     # For some reason the makefile sets "AR = libtool" on Darwin.
-    ++ stdenv.lib.optional (builtins.currentSystem == "i686-darwin") libtool;
+    ++ stdenv.lib.optional (stdenv.system == "i686-darwin") libtool;
 
   # Unpack the thing in a subdirectory.
   unpackPhase = ''