diff --git a/lib/bb/parse/ast.py b/lib/bb/parse/ast.py
index 3250211e607..2a98809fa5b 100644
--- a/lib/bb/parse/ast.py
+++ b/lib/bb/parse/ast.py
@@ -363,7 +363,8 @@ class AddFragmentsNode(AstNode):
         def check_and_set_builtin_fragment(fragment, data, builtin_fragments):
             prefix, value = fragment.split('/', 1)
             if prefix in builtin_fragments.keys():
-                data.setVar(builtin_fragments[prefix], value)
+                # parsing=True since we want to emulate X=Y and allow X:override=Z to continue to exist
+                data.setVar(builtin_fragments[prefix], value, parsing=True)
                 return True
             return False