diff --git a/binderhub/binderspawner_mixin.py b/binderhub/binderspawner_mixin.py
index 175e1d56a..aaa4761f8 100644
--- a/binderhub/binderspawner_mixin.py
+++ b/binderhub/binderspawner_mixin.py
@@ -84,6 +84,10 @@ def get_args(self):
             if self.cors_allow_origin == "*":
                 args.append("--NotebookApp.allow_origin_pat=.*")
             args += self.args
+            # ServerApp compatibility: duplicate NotebookApp args
+            for arg in list(args):
+                if arg.startswith("--NotebookApp."):
+                    args.append(arg.replace("--NotebookApp.", "--ServerApp."))
         return args
 
     def start(self):
diff --git a/helm-chart/binderhub/values.yaml b/helm-chart/binderhub/values.yaml
index dde5b7a68..0b3139be9 100644
--- a/helm-chart/binderhub/values.yaml
+++ b/helm-chart/binderhub/values.yaml
@@ -169,6 +169,10 @@ jupyterhub:
                     if self.cors_allow_origin == "*":
                         args.append("--NotebookApp.allow_origin_pat=.*")
                     args += self.args
+                    # ServerApp compatibility: duplicate NotebookApp args
+                    for arg in list(args):
+                        if arg.startswith("--NotebookApp."):
+                            args.append(arg.replace("--NotebookApp.", "--ServerApp."))
                 return args
 
             def start(self):