diff --git a/pkgs/development/interpreters/ruby/ruby-1.9.3.nix b/pkgs/development/interpreters/ruby/ruby-1.9.3.nix
index 9f7252bdc48..c812abc70fe 100644
--- a/pkgs/development/interpreters/ruby/ruby-1.9.3.nix
+++ b/pkgs/development/interpreters/ruby/ruby-1.9.3.nix
@@ -48,12 +48,6 @@ stdenv.mkDerivation rec {
 
   enableParallelBuilding = true;
 
-  # Fix a build failure on systems with nix store optimisation.
-  # (The build process attempted to copy file a overwriting file b, where a and
-  # b are hard-linked, which results in cp returning a non-zero exit code.)
-  # https://github.com/NixOS/nixpkgs/issues/4266
-  postUnpack = ''rm "$sourceRoot/enc/unicode/name2ctype.h"'';
-
   patches = [
     ./ruby19-parallel-install.patch
     ./bitperfect-rdoc.patch
diff --git a/pkgs/development/interpreters/ruby/ruby-2.0.0.nix b/pkgs/development/interpreters/ruby/ruby-2.0.0.nix
index 6e85d6c0330..1e886b0219a 100644
--- a/pkgs/development/interpreters/ruby/ruby-2.0.0.nix
+++ b/pkgs/development/interpreters/ruby/ruby-2.0.0.nix
@@ -50,12 +50,6 @@ stdenv.mkDerivation rec {
 
   enableParallelBuilding = true;
 
-  # Fix a build failure on systems with nix store optimisation.
-  # (The build process attempted to copy file a overwriting file b, where a and
-  # b are hard-linked, which results in cp returning a non-zero exit code.)
-  # https://github.com/NixOS/nixpkgs/issues/4266
-  postUnpack = ''rm "$sourceRoot/enc/unicode/name2ctype.h"'';
-
   patches = ops useRailsExpress [
     "${patchSet}/patches/ruby/2.0.0/p481/01-zero-broken-tests.patch"
     "${patchSet}/patches/ruby/2.0.0/p481/02-railsexpress-gc.patch"
diff --git a/pkgs/development/interpreters/ruby/ruby-2.1.0.nix b/pkgs/development/interpreters/ruby/ruby-2.1.0.nix
index 39884745635..8467bc4eb38 100644
--- a/pkgs/development/interpreters/ruby/ruby-2.1.0.nix
+++ b/pkgs/development/interpreters/ruby/ruby-2.1.0.nix
@@ -51,12 +51,6 @@ stdenv.mkDerivation rec {
 
   enableParallelBuilding = true;
 
-  # Fix a build failure on systems with nix store optimisation.
-  # (The build process attempted to copy file a overwriting file b, where a and
-  # b are hard-linked, which results in cp returning a non-zero exit code.)
-  # https://github.com/NixOS/nixpkgs/issues/4266
-  postUnpack = ''rm "$sourceRoot/enc/unicode/name2ctype.h"'';
-
   patches = ops useRailsExpress [
     "${patchSet}/patches/ruby/2.1.0/railsexpress/01-current-2.1.1-fixes.patch"
     "${patchSet}/patches/ruby/2.1.0/railsexpress/02-zero-broken-tests.patch"
diff --git a/pkgs/development/interpreters/ruby/ruby-2.1.1.nix b/pkgs/development/interpreters/ruby/ruby-2.1.1.nix
index eb8239086ea..e26cdd5b315 100644
--- a/pkgs/development/interpreters/ruby/ruby-2.1.1.nix
+++ b/pkgs/development/interpreters/ruby/ruby-2.1.1.nix
@@ -51,12 +51,6 @@ stdenv.mkDerivation rec {
 
   enableParallelBuilding = true;
 
-  # Fix a build failure on systems with nix store optimisation.
-  # (The build process attempted to copy file a overwriting file b, where a and
-  # b are hard-linked, which results in cp returning a non-zero exit code.)
-  # https://github.com/NixOS/nixpkgs/issues/4266
-  postUnpack = ''rm "$sourceRoot/enc/unicode/name2ctype.h"'';
-
   patches = ops useRailsExpress [
     "${patchSet}/patches/ruby/2.1.0/railsexpress/01-zero-broken-tests.patch"
     "${patchSet}/patches/ruby/2.1.0/railsexpress/02-improve-gc-stats.patch"
diff --git a/pkgs/development/interpreters/ruby/ruby-2.1.2.nix b/pkgs/development/interpreters/ruby/ruby-2.1.2.nix
index 2cefa6b002a..fe03b86d86d 100644
--- a/pkgs/development/interpreters/ruby/ruby-2.1.2.nix
+++ b/pkgs/development/interpreters/ruby/ruby-2.1.2.nix
@@ -51,12 +51,6 @@ stdenv.mkDerivation rec {
 
   enableParallelBuilding = true;
 
-  # Fix a build failure on systems with nix store optimisation.
-  # (The build process attempted to copy file a overwriting file b, where a and
-  # b are hard-linked, which results in cp returning a non-zero exit code.)
-  # https://github.com/NixOS/nixpkgs/issues/4266
-  postUnpack = ''rm "$sourceRoot/enc/unicode/name2ctype.h"'';
-
   patches = ops useRailsExpress [
     "${patchSet}/patches/ruby/2.1.2/railsexpress/01-zero-broken-tests.patch"
     "${patchSet}/patches/ruby/2.1.2/railsexpress/02-improve-gc-stats.patch"