diff --git a/test/posthog/feature_flags_test.exs b/test/posthog/feature_flags_test.exs
index 8103de3..057217e 100644
--- a/test/posthog/feature_flags_test.exs
+++ b/test/posthog/feature_flags_test.exs
@@ -1,5 +1,6 @@
 defmodule PostHog.FeatureFlagsTest do
-  use PostHog.Case, async: true, group: PostHog
+  # group only works for Elixir 1.18, can't make it async until then
+  use PostHog.Case, async: false, group: PostHog
 
   @moduletag config: [supervisor_name: PostHog]
 
diff --git a/test/posthog_test.exs b/test/posthog_test.exs
index 5faa8d2..ce83d91 100644
--- a/test/posthog_test.exs
+++ b/test/posthog_test.exs
@@ -1,5 +1,6 @@
 defmodule PostHogTest do
-  use PostHog.Case, async: true, group: PostHog
+  # group only works for Elixir 1.18, can't make it async until then
+  use PostHog.Case, async: false, group: PostHog
 
   @moduletag config: [supervisor_name: PostHog]