diff --git a/rustler_tests/test/env_test.exs b/rustler_tests/test/env_test.exs
index fab1c0bd..54923a07 100644
--- a/rustler_tests/test/env_test.exs
+++ b/rustler_tests/test/env_test.exs
@@ -25,7 +25,7 @@ defmodule RustlerTest.EnvTest do
         receive do
           # Collect the pids that the child processes send back.
           {child_pid, {:hello, :world}} -> child_pid
-          _ -> raise :fail
+          _ -> raise "fail"
         end
       end
 
diff --git a/rustler_tests/test/thread_test.exs b/rustler_tests/test/thread_test.exs
index fdbecdf8..08730dc1 100644
--- a/rustler_tests/test/thread_test.exs
+++ b/rustler_tests/test/thread_test.exs
@@ -13,7 +13,7 @@ defmodule RustlerTest.ThreadTest do
     RustlerTest.threaded_sleep(200)
 
     receive do
-      _ -> raise :timeout_expected
+      _ -> raise "timeout_expected"
     after
       100 ->
         nil
@@ -23,7 +23,7 @@ defmodule RustlerTest.ThreadTest do
       x -> assert x == 200
     after
       1000 ->
-        raise :message_expected
+        raise "message_expected"
     end
   end