diff --git a/pkgs/development/tools/java/sawjap/default.nix b/pkgs/development/tools/java/sawjap/default.nix
index 13532c48d40..b4c682bbd22 100644
--- a/pkgs/development/tools/java/sawjap/default.nix
+++ b/pkgs/development/tools/java/sawjap/default.nix
@@ -8,7 +8,7 @@ stdenv.mkDerivation {
 
   inherit (sawja) src version;
 
-  sourceRoot = "source/test";
+  prePatch = "cd test";
 
   buildInputs = [ ocaml findlib sawja ];