diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index e4fb56959..67c09ac5d 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [windows-latest, ubuntu-22.04, macos-latest-large]
+        os: [windows-latest, ubuntu-22.04, macos-latest]
 
     steps:
     - name: Install tools
diff --git a/tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini b/tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini
index 8fbc70f1b..25b455163 100644
--- a/tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini
+++ b/tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini
@@ -150,6 +150,7 @@ RunCondition=NOT $(IS_MONO) # Mono codepage 852 encoding incorrecly decodes 0xAA
 IsolationLevel=PROCESS # reset reporting of warnings
 
 [IronPython.test_utf8_mode_stdlib]
+Timeout=240000 # Mono is extremely slow
 IsolationLevel=PROCESS
 
 [IronPython.interop.net.derivation.test_property_override]