diff --git a/pkgs/development/libraries/adns/1.1.nix b/pkgs/development/libraries/adns/1.1.nix
index 2eab5b7dd7dd..311862d3b9f9 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 8afb5067803a..1340f790ed14 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 b34eb4d3a700..ccc6fa563edf 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 dad2dd678231..d82b8aec9025 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";