diff --git a/pkgs/development/interpreters/python/cpython/3.6/default.nix b/pkgs/development/interpreters/python/cpython/3.6/default.nix
index 7ccd4fcede68..ebf621d50576 100644
--- a/pkgs/development/interpreters/python/cpython/3.6/default.nix
+++ b/pkgs/development/interpreters/python/cpython/3.6/default.nix
@@ -1,6 +1,8 @@
 { stdenv, fetchurl, fetchpatch
 , glibc
 , bzip2
+, expat
+, libffi
 , gdbm
 , lzma
 , ncurses
@@ -86,6 +88,8 @@ in stdenv.mkDerivation {
     "--enable-shared"
     "--with-threads"
     "--without-ensurepip"
+    "--with-system-expat"
+    "--with-system-ffi"
   ];
 
   preConfigure = ''