diff --git a/tests.yml b/tests.yml
index 9d49567..3c11dde 100644
--- a/tests.yml
+++ b/tests.yml
@@ -57,7 +57,7 @@
         run: VERSION=3.8 PYTHON="python3-debug" X="test_ssl" ./parallel.sh
     - debugflags:
         dir: flags
-        run: python3-debug ./assertflags.py -Og
+        run: python3-debug ./assertflags.py -O0
     - marshalparser_compatibility:
         dir: marshalparser
         run: SAMPLE=10 test_marshalparser_compatibility.sh