diff --git a/pkgs/development/compilers/mlton/default.nix b/pkgs/development/compilers/mlton/default.nix
index aaf588851402..67dfd3d26898 100644
--- a/pkgs/development/compilers/mlton/default.nix
+++ b/pkgs/development/compilers/mlton/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, fetchgit, patchelf, gmp }:
+{ stdenv, fetchurl, fetchgit, patchelf, gmp, which }:
 rec {
   mlton20130715 = import ./20130715.nix {
     inherit stdenv fetchurl patchelf gmp;
@@ -13,7 +13,7 @@ rec {
     version = "20180207";
     rev = "on-20180207-release";
     sha256 = "00rdd2di5x1dzac64il9z05m3fdzicjd3226wwjyynv631jj3q2a";
-    inherit stdenv fetchgit gmp;
+    inherit stdenv fetchgit gmp which;
   };
 
   mltonHEAD = import ./from-git-source.nix {
@@ -21,6 +21,6 @@ rec {
     version = "HEAD";
     rev = "e149c9917cfbfe6aba5c986a958ed76d5cc6cfde";
     sha256 = "0a0j1i0f0fxw2my1309srq5j3vz0kawrrln01gxms2m5hy5dl50d";
-    inherit stdenv fetchgit gmp;
+    inherit stdenv fetchgit gmp which;
   };
 }
diff --git a/pkgs/development/compilers/mlton/from-git-source.nix b/pkgs/development/compilers/mlton/from-git-source.nix
index 2585b599caf3..dc5862e6e3d8 100644
--- a/pkgs/development/compilers/mlton/from-git-source.nix
+++ b/pkgs/development/compilers/mlton/from-git-source.nix
@@ -6,6 +6,7 @@
 , sha256
 , stdenv
 , version
+, which
 }:
 
 stdenv.mkDerivation {
@@ -16,6 +17,8 @@ stdenv.mkDerivation {
     inherit url rev sha256;
   };
 
+  nativeBuildInputs = [ which ];
+
   buildInputs = [mltonBootstrap gmp];
 
   preBuild = ''