diff --git a/pkgs/development/interpreters/elixir/default.nix b/pkgs/development/interpreters/elixir/default.nix
index a6fc139e2e5f..9a5d2417df7b 100644
--- a/pkgs/development/interpreters/elixir/default.nix
+++ b/pkgs/development/interpreters/elixir/default.nix
@@ -20,7 +20,7 @@ stdenv.mkDerivation {
 
     substituteInPlace Makefile \
       --replace "/usr/local" $out
-    substituteInPlace bin//mix \
+    substituteInPlace bin/mix \
       --replace "/usr/bin/env elixir" "$out/bin/elixir"
   '';