diff --git a/pkgs/development/libraries/libidn/default.nix b/pkgs/development/libraries/libidn/default.nix
index 99efc66aa411..c2da099f6703 100644
--- a/pkgs/development/libraries/libidn/default.nix
+++ b/pkgs/development/libraries/libidn/default.nix
@@ -1,11 +1,11 @@
 { fetchurl, stdenv }:
 
 stdenv.mkDerivation rec {
-  name = "libidn-1.20";
+  name = "libidn-1.21";
 
   src = fetchurl {
     url = "mirror://gnu/libidn/${name}.tar.gz";
-    sha256 = "1cd8zixibvci99gwc5cg0b8728y7daysrxcfa1j11qfwx1rg9gz1";
+    sha256 = "1hspbi2p8y3nqkgj8q1myyhwmshxjxdkg54a8axhbb8lpvkr66l6";
   };
 
   doCheck = true;