diff --git a/pkgs/build-support/fetchsvn/default.nix b/pkgs/build-support/fetchsvn/default.nix
index 131dd5d756c2..dd8f7b41f781 100644
--- a/pkgs/build-support/fetchsvn/default.nix
+++ b/pkgs/build-support/fetchsvn/default.nix
@@ -9,6 +9,7 @@ stdenv.mkDerivation {
   id = md5;
 
   outputHashAlgo = "md5";
+  outputHashMode = "recursive";
   outputHash = md5;
   
   inherit url rev;