diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 3dffdb3..e109b5c 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -136,6 +136,9 @@ jobs:
       - name: Install Dependencies
         run: nix develop --command bash -c "mix deps.get"
 
+      - name: Compile with --warnings-as-errors
+        run: nix develop --command bash -c "mix compile --warnings-as-errors"
+
       - name: Run Formatter
         run: nix develop --command bash -c "mix format --check-formatted"
 
diff --git a/lib/spitfire.ex b/lib/spitfire.ex
index 2befcbb..4e67054 100644
--- a/lib/spitfire.ex
+++ b/lib/spitfire.ex
@@ -299,7 +299,7 @@ defmodule Spitfire do
 
   @terminals MapSet.new([:eol, :eof, :"}", :")", :"]", :">>", :block_identifier])
   @terminals_with_comma MapSet.put(@terminals, :",")
-  defp parse_expression(parser, assoc \\ @lowest, is_list \\ false, is_map \\ false, is_top \\ false)
+  defp parse_expression(parser, assoc, is_list, is_map, is_top)
 
   defp parse_expression(parser, {associativity, precedence}, is_list, is_map, is_top) do
     trace "parse_expression", trace_meta(parser) do