diff --git a/Makefile b/Makefile
index 6ae88b26..e47b180f 100644
--- a/Makefile
+++ b/Makefile
@@ -319,7 +319,7 @@ check.coverage.local: check.coverage.misc check.coverage.postgres.local check.co
 	$(MAKE) check.coverage.combine
 
 IS_DOCKER	=
-FAIL_UNDER  = $(shell python -c 'import sys; print(100.0 if sys.version_info < (3, 13) else 84.6)')
+FAIL_UNDER  = $(shell python -c 'import sys; import platform; print(100.0 if sys.version_info < (3, 13) and platform.python_implementation() == "CPython" else 84.6)')
 
 .PHONY: check.coverage.combine
 check.coverage.combine: $(VENV)