diff --git a/pkgs/development/libraries/adns/1.1.nix b/pkgs/development/libraries/adns/1.1.nix
index 2eab5b7dd7d..311862d3b9f 100644
--- a/pkgs/development/libraries/adns/1.1.nix
+++ b/pkgs/development/libraries/adns/1.1.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, version, static }:
+{ stdenv, fetchurl, version ? "1.1", static }:
 
 assert version == "1.1";
 
diff --git a/pkgs/development/libraries/adns/1.2.nix b/pkgs/development/libraries/adns/1.2.nix
index 8afb5067803..1340f790ed1 100644
--- a/pkgs/development/libraries/adns/1.2.nix
+++ b/pkgs/development/libraries/adns/1.2.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, version, static }:
+{ stdenv, fetchurl, version ? "1.2", static }:
 
 assert version == "1.2";
 
diff --git a/pkgs/development/libraries/adns/1.3.nix b/pkgs/development/libraries/adns/1.3.nix
index b34eb4d3a70..ccc6fa563ed 100644
--- a/pkgs/development/libraries/adns/1.3.nix
+++ b/pkgs/development/libraries/adns/1.3.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, version, static }:
+{ stdenv, fetchurl, version ? "1.3", static }:
 
 assert version == "1.3";
 
diff --git a/pkgs/development/libraries/adns/1.4.nix b/pkgs/development/libraries/adns/1.4.nix
index dad2dd67823..d82b8aec902 100644
--- a/pkgs/development/libraries/adns/1.4.nix
+++ b/pkgs/development/libraries/adns/1.4.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, version, static }:
+{ stdenv, fetchurl, version ? "1.4", static }:
 
 assert version == "1.4";