diff --git a/pkgs/build-support/fetchurl/default.nix b/pkgs/build-support/fetchurl/default.nix
index 4d0f525a15c59..082776e9b58fa 100644
--- a/pkgs/build-support/fetchurl/default.nix
+++ b/pkgs/build-support/fetchurl/default.nix
@@ -164,12 +164,6 @@ lib.extendMkDerivation {
         else
           throw "fetchurl requires either `url` or `urls` to be set: ${lib.generators.toPretty { } args}";
 
-      urls_ =
-        let
-          u = lib.lists.filter (url: lib.isString url) (map rewriteURL preRewriteUrls);
-        in
-        if u == [ ] then throw "urls is empty after rewriteURL (was ${toString preRewriteUrls})" else u;
-
       hash_ =
         if
           with lib.lists;
@@ -183,7 +177,7 @@ lib.extendMkDerivation {
             ]
           ) > 1
         then
-          throw "multiple hashes passed to fetchurl: ${lib.generators.toPretty { } urls_}"
+          throw "multiple hashes passed to fetchurl: ${lib.generators.toPretty { } finalAttrs.urls}"
         else
 
         if hash != "" then
@@ -195,7 +189,9 @@ lib.extendMkDerivation {
           if outputHashAlgo != "" then
             { inherit outputHashAlgo outputHash; }
           else
-            throw "fetchurl was passed outputHash without outputHashAlgo: ${lib.generators.toPretty { } urls_}"
+            throw "fetchurl was passed outputHash without outputHashAlgo: ${
+              lib.generators.toPretty { } finalAttrs.urls
+            }"
         else if sha512 != "" then
           {
             outputHashAlgo = "sha512";
@@ -217,7 +213,9 @@ lib.extendMkDerivation {
             outputHash = lib.fakeHash;
           }
         else
-          throw "fetchurl requires a hash for fixed-output derivation: ${lib.generators.toPretty { } urls_}";
+          throw "fetchurl requires a hash for fixed-output derivation: ${
+            lib.generators.toPretty { } finalAttrs.urls
+          }";
 
       finalHashHasColon = lib.hasInfix ":" finalAttrs.hash;
       finalHashColonMatch = lib.match "([^:]+)[:](.*)" finalAttrs.hash;
@@ -243,18 +241,22 @@ lib.extendMkDerivation {
       name =
         if finalAttrs.pname or null != null && finalAttrs.version or null != null then
           "${finalAttrs.pname}-${finalAttrs.version}"
-        else if showURLs then
+        else if finalAttrs.showURLs then
           "urls"
         else if name != null then
           name
         else
-          baseNameOf (toString (lib.head urls_));
+          baseNameOf (toString (lib.head finalAttrs.urls));
 
       builder = ./builder.sh;
 
       nativeBuildInputs = [ curl ] ++ nativeBuildInputs;
 
-      urls = urls_;
+      urls =
+        let
+          u = lib.lists.filter (url: lib.isString url) (map rewriteURL preRewriteUrls);
+        in
+        if u == [ ] then throw "urls is empty after rewriteURL (was ${toString preRewriteUrls})" else u;
 
       # If set, prefer the content-addressable mirrors
       # (http://tarballs.nixos.org) over the original URLs.
@@ -288,18 +290,19 @@ lib.extendMkDerivation {
             || hash_.outputHash == lib.fakeSha256
             || hash_.outputHash == lib.fakeSha512
             || hash_.outputHash == lib.fakeHash
-            || netrcPhase != null
+            || finalAttrs.netrcPhase != null
           )
         then
           "${cacert}/etc/ssl/certs/ca-bundle.crt"
         else
           "/no-cert-file.crt";
 
-      outputHashMode = if (recursiveHash || executable) then "recursive" else "flat";
+      outputHashMode =
+        if (finalAttrs.recursiveHash || finalAttrs.executable) then "recursive" else "flat";
 
       curlOpts = lib.warnIf (lib.isList curlOpts) (
         let
-          url = toString (builtins.head urls_);
+          url = toString (builtins.head finalAttrs.urls);
           curlOptsRepresentation = lib.generators.toPretty { multiline = false; } curlOpts;
           curlOptsAsStringRepresentation = lib.strings.escapeNixString (toString curlOpts);
           curlOptsListElementsRepresentation =
@@ -318,25 +321,28 @@ lib.extendMkDerivation {
       curlOptsList = lib.escapeShellArgs curlOptsList;
 
       inherit
-        showURLs
-        mirrorsFile
-        postFetch
         downloadToTemp
         executable
+        mirrorsFile
+        netrcImpureEnvVars
+        netrcPhase
+        postFetch
+        recursiveHash
+        showURLs
         ;
 
-      impureEnvVars = impureEnvVars ++ netrcImpureEnvVars;
+      impureEnvVars = impureEnvVars ++ finalAttrs.netrcImpureEnvVars;
 
       nixpkgsVersion = lib.trivial.release;
 
       inherit preferLocalBuild;
 
       postHook =
-        if netrcPhase == null then
+        if finalAttrs.netrcPhase == null then
           null
         else
           ''
-            ${netrcPhase}
+            ${finalAttrs.netrcPhase}
             curlOpts="$curlOpts --netrc-file $PWD/netrc"
           '';