diff --git a/pkgs/top-level/perl-packages.nix b/pkgs/top-level/perl-packages.nix
index fe790e2caee..b316c746ac1 100644
--- a/pkgs/top-level/perl-packages.nix
+++ b/pkgs/top-level/perl-packages.nix
@@ -194,7 +194,7 @@ let
     pname = "Alien-Libxml2";
     version = "0.16";
     src = fetchurl {
-      url = mirror://cpan/authors/id/P/PL/PLICEASE/Alien-Libxml2-0.16.tar.gz;
+      url = "mirror://cpan/authors/id/P/PL/PLICEASE/Alien-Libxml2-0.16.tar.gz";
       sha256 = "15rvllspikyr8412v8dpl2f2w5vxnjgnddnkz378sy2g0mc6mw2n";
     };
     propagatedBuildInputs = [ AlienBuild ];