diff --git a/pkgs/tools/system/which/default.nix b/pkgs/tools/system/which/default.nix
index b6c35c4fbf12..7420cce0e543 100644
--- a/pkgs/tools/system/which/default.nix
+++ b/pkgs/tools/system/which/default.nix
@@ -1,8 +1,8 @@
 {stdenv, fetchurl, readline}: stdenv.mkDerivation {
-  name = "which-2.19";
+  name = "which-2.20";
   src = fetchurl {
-    url = mirror://gnu/which/which-2.19.tar.gz;
-    sha256 = "0lnd8mfpc0r1r2ch54vl3vc6r0fnzfl33sqdda2aq62iyrsbhybx";
+    url = mirror://gnu/which/which-2.20.tar.gz;
+    sha256 = "1y2p50zadb36izzh2zw4dm5hvdiydqf3qa88l8kav20dcmfbc5yl";
   };
 
   buildInputs = [readline];