diff --git a/elm.nix b/elm.nix
index fc33d9d..6080626 100644
--- a/elm.nix
+++ b/elm.nix
@@ -29,7 +29,7 @@ let
         mkdir -p $out/share/doc
         ${lib.concatStrings (map (module: ''
           echo "compiling ${elmfile module}"
-          elm make ${elmfile module} --output $out/${module}.${extension} --docs $out/share/doc/${module}.json
+          elm make ${elmfile module} --output $out/${module}.${extension} --docs $out/share/doc/${module}.json --optimize
           ${lib.optionalString outputJavaScript ''
             echo "minifying ${elmfile module}"
             uglifyjs $out/${module}.${extension} --compress 'pure_funcs="F2,F3,F4,F5,F6,F7,F8,F9,A2,A3,A4,A5,A6,A7,A8,A9",pure_getters,keep_fargs=false,unsafe_comps,unsafe' \