diff --git a/.github/workflows/elixir.yml b/.github/workflows/elixir.yml
index 4edba995d7..5ead5a982c 100644
--- a/.github/workflows/elixir.yml
+++ b/.github/workflows/elixir.yml
@@ -2,9 +2,9 @@ name: CI
 
 on:
   push:
-  pull_request:
     branches:
       - main
+  pull_request:
 
 jobs:
   test:
@@ -17,21 +17,21 @@ jobs:
           - '1.15'
           - '1.16'
           - '1.17'
+          - '1.18'
         otp:
           - '25'
           - '26'
           - '27'
+        # see https://hexdocs.pm/elixir/compatibility-and-deprecations.html#between-elixir-and-erlang-otp
         exclude:
-          - otp: 25
-            elixir: 1.17
-          - otp: 27
-            elixir: 1.15
-          - otp: 27
-            elixir: 1.16
+          - elixir: 1.16
+            otp: 27
+          - elixir: 1.15
+            otp: 27
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Set up Elixir
         uses: erlef/setup-beam@v1
@@ -40,7 +40,7 @@ jobs:
           otp-version: ${{ matrix.otp }}
 
       - name: Restore deps cache
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: |
             deps
@@ -69,7 +69,7 @@ jobs:
           SCHEMA_PROVIDER: persistent_term
 
       - name: Cache/uncache PLTs
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: |
             priv/plts
diff --git a/lib/absinthe/utils/render.ex b/lib/absinthe/utils/render.ex
index 51e44bda6f..1052213d71 100644
--- a/lib/absinthe/utils/render.ex
+++ b/lib/absinthe/utils/render.ex
@@ -48,7 +48,7 @@ defmodule Absinthe.Utils.Render do
   end
 
   defp escape_string(<<char::utf8, rest::binary>>, acc) do
-    escape_string(rest, [acc | <<char::utf8>>])
+    escape_string(rest, acc ++ [<<char::utf8>>])
   end
 
   defp escape_string(<<>>, acc) do