diff --git a/pkgs/development/beam-modules/fetch-rebar-deps.nix b/pkgs/development/beam-modules/fetch-rebar-deps.nix
index 31bef024d320..eee8f3729bd4 100644
--- a/pkgs/development/beam-modules/fetch-rebar-deps.nix
+++ b/pkgs/development/beam-modules/fetch-rebar-deps.nix
@@ -15,11 +15,12 @@ stdenv.mkDerivation ({
 
   dontUnpack = true;
   dontConfigure = true;
-  dontBuild = true;
   dontFixup = true;
 
-  prePhases = ''
-    cp ${src} .
+  buildPhase = ''
+    cp -r ${src} src
+    chmod -R u+w src
+    cd src
     HOME='.' DEBUG=1 ${rebar3}/bin/rebar3 get-deps
   '';