diff --git a/bitbake/lib/bb/event.py b/bitbake/lib/bb/event.py
index a12adbc937..b29f0a5568 100644
--- a/bitbake/lib/bb/event.py
+++ b/bitbake/lib/bb/event.py
@@ -431,6 +431,16 @@ class RecipeEvent(Event):
         self.fn = fn
         Event.__init__(self)
 
+class RecipePreDeferredInherits(RecipeEvent):
+    """
+    Called before deferred inherits are processed so code can snoop on class extensions for example
+    Limitations: It won't see inherits of inherited classes and the data is unexpanded
+    """
+    def __init__(self, fn, inherits):
+        self.fn = fn
+        self.inherits = inherits
+        Event.__init__(self)
+
 class RecipePreFinalise(RecipeEvent):
     """ Recipe Parsing Complete but not yet finalised"""
 
diff --git a/bitbake/lib/bb/parse/ast.py b/bitbake/lib/bb/parse/ast.py
index f9998798d8..5a086b4e95 100644
--- a/bitbake/lib/bb/parse/ast.py
+++ b/bitbake/lib/bb/parse/ast.py
@@ -471,6 +471,9 @@ def finalize(fn, d, variant = None):
         if d.getVar("_FAILPARSINGERRORHANDLED", False) == True:
             raise bb.BBHandledException()
 
+        inherits = [x[0] for x in (d.getVar('__BBDEFINHERITS', False) or [('',)])]
+        bb.event.fire(bb.event.RecipePreDeferredInherits(fn, inherits), d)
+
         while True:
             inherits = d.getVar('__BBDEFINHERITS', False) or []
             if not inherits: