diff --git a/pkgs/build-support/fetchurl/default.nix b/pkgs/build-support/fetchurl/default.nix
index c65738aef41a..8ce69a7f1878 100644
--- a/pkgs/build-support/fetchurl/default.nix
+++ b/pkgs/build-support/fetchurl/default.nix
@@ -104,7 +104,9 @@ let
     if urls != [] && url == "" then
       (if lib.isList urls then urls
        else throw "`urls` is not a list")
-    else if urls == [] && url != "" then [url]
+    else if urls == [] && url != "" then
+      (if lib.isString url then [url]
+       else throw "`url` is not a string")
     else throw "fetchurl requires either `url` or `urls` to be set";
 
   hash_ =
diff --git a/pkgs/development/tools/misc/intltool/default.nix b/pkgs/development/tools/misc/intltool/default.nix
index 7a3379d59217..967fc442a73d 100644
--- a/pkgs/development/tools/misc/intltool/default.nix
+++ b/pkgs/development/tools/misc/intltool/default.nix
@@ -12,7 +12,7 @@ stdenv.mkDerivation rec {
   # fix "unescaped left brace" errors when using intltool in some cases
   patches = [(fetchpatch {
     name = "perl5.26-regex-fixes.patch";
-    url = [
+    urls = [
       "https://sources.debian.org/data/main/i/intltool/0.51.0-5/debian/patches/perl5.26-regex-fixes.patch"
       "https://src.fedoraproject.org/rpms/intltool/raw/d8d2ef29fb122a42a6b6678eb1ec97ae56902af2/f/intltool-perl5.26-regex-fixes.patch"
     ];