diff --git a/default.nix b/default.nix
index 84bb1af84e9..e0df520721c 100644
--- a/default.nix
+++ b/default.nix
@@ -1,6 +1,6 @@
-if ! builtins ? nixVersion || builtins.compareVersions "1.8" builtins.nixVersion == 1 then
+if ! builtins ? nixVersion || builtins.compareVersions "1.7" builtins.nixVersion == 1 then
 
-  abort "This version of Nixpkgs requires Nix >= 1.8, please upgrade!"
+  abort "This version of Nixpkgs requires Nix >= 1.7, please upgrade!"
 
 else
 
diff --git a/lib/customisation.nix b/lib/customisation.nix
index f16043cf9a3..04a5cb42033 100644
--- a/lib/customisation.nix
+++ b/lib/customisation.nix
@@ -65,13 +65,6 @@ rec {
           overrideDerivation = fdrv:
             makeOverridable (args: overrideDerivation (f args) fdrv) origArgs;
         })
-      else if builtins.isFunction ff then
-        { override = newArgs:
-            makeOverridable f (origArgs // (if builtins.isFunction newArgs then newArgs origArgs else newArgs));
-          __functor = self: ff;
-          deepOverride = throw "deepOverride not yet supported for functors";
-          overrideDerivation = throw "overrideDerivation not yet supported for functors";
-        }
       else ff;
 
   deepOverrider = newArgs: name: x: if builtins.isAttrs x then (