diff --git a/pkgs/development/web/mailcatcher/default.nix b/pkgs/development/web/mailcatcher/default.nix
index 7b19d02103dc..49c5c4d81af1 100644
--- a/pkgs/development/web/mailcatcher/default.nix
+++ b/pkgs/development/web/mailcatcher/default.nix
@@ -15,7 +15,7 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ makeWrapper ];
 
-  phases = ["installPhase"];
+  unpackPhase = ":";
 
   installPhase = ''
     mkdir -p $out/bin