1 files changed, 1 insertions, 1 deletions
diff --git a/nixpkgs/pkgs/applications/science/logic/isabelle/default.nix b/nixpkgs/pkgs/applications/science/logic/isabelle/default.nix
index 024f2f4e8294..d2e49d817837 100644
--- a/nixpkgs/pkgs/applications/science/logic/isabelle/default.nix
+++ b/nixpkgs/pkgs/applications/science/logic/isabelle/default.nix
@@ -74,7 +74,7 @@ stdenv.mkDerivation rec {
       to be expressed in a formal language and provides tools for proving those
       formulas in a logical calculus.
     '';
-    homepage = http://isabelle.in.tum.de/;
+    homepage = "http://isabelle.in.tum.de/";
     license = "LGPL";
     maintainers = [ stdenv.lib.maintainers.jwiegley ];
     platforms = stdenv.lib.platforms.linux;