diff --git a/bitbake/lib/bb/parse/parse_py/BBHandler.py b/bitbake/lib/bb/parse/parse_py/BBHandler.py
index 76b917ca5d..915db214f5 100644
--- a/bitbake/lib/bb/parse/parse_py/BBHandler.py
+++ b/bitbake/lib/bb/parse/parse_py/BBHandler.py
@@ -329,7 +329,8 @@ def feeder(lineno, s, fn, root, d):
         after = m.group("after")
         if func is None:
             return
-        var = "do_" + func
+        if func[:3] != "do_":
+            var = "do_" + func
 
         data.setVarFlag(var, "task", 1, d)