diff --git a/pkgs/top-level/perl-packages.nix b/pkgs/top-level/perl-packages.nix
index 13bdb823e22..d809c52cc96 100644
--- a/pkgs/top-level/perl-packages.nix
+++ b/pkgs/top-level/perl-packages.nix
@@ -18307,7 +18307,7 @@ let
     pname = "System-Command";
     version = "1.121";
     src = fetchurl {
-      url = mirror://cpan/authors/id/B/BO/BOOK/System-Command-1.121.tar.gz;
+      url = "mirror://cpan/authors/id/B/BO/BOOK/System-Command-1.121.tar.gz";
       sha256 = "43de5ecd20c1da46e8a6f4fceab29e04697a2890a99bf6a91b3ca004a468a241";
     };
     propagatedBuildInputs = [ IPCRun ];