diff --git a/lib/galaxy/tool_util/cwl/parser.py b/lib/galaxy/tool_util/cwl/parser.py
index 48fca34a3fb4..1914c2e63e61 100644
--- a/lib/galaxy/tool_util/cwl/parser.py
+++ b/lib/galaxy/tool_util/cwl/parser.py
@@ -258,7 +258,7 @@ def check_requirements(rec, tool=True):
             check_requirements(d, tool=tool)
 
 
-class ToolProxy(ABCMeta):
+class ToolProxy(metaclass=ABCMeta):
 
     _class: str