diff --git a/spectree/plugins/falcon_plugin.py b/spectree/plugins/falcon_plugin.py
index 892661eb..8539f0b7 100644
--- a/spectree/plugins/falcon_plugin.py
+++ b/spectree/plugins/falcon_plugin.py
@@ -70,12 +70,11 @@ def __init__(self, spectree):
         self.INT_ARGS_NAMES = ("num_digits", "min", "max")
 
     def register_route(self, app: Any):
-        self.app = app
-        self.app.add_route(
+        app.add_route(
             self.config.spec_url, self.OPEN_API_ROUTE_CLASS(self.spectree.spec)
         )
         for ui in self.config.page_templates:
-            self.app.add_route(
+            app.add_route(
                 f"/{self.config.path}/{ui}",
                 self.DOC_PAGE_ROUTE_CLASS(
                     self.config.page_templates[ui],
@@ -95,7 +94,7 @@ def find_node(node):
             for child in node.children:
                 find_node(child)
 
-        for route in self.app._router._roots:
+        for route in self.spectree.app._router._roots:
             find_node(route)
 
         return routes
diff --git a/spectree/plugins/starlette_plugin.py b/spectree/plugins/starlette_plugin.py
index f0ef2226..c9d0c391 100644
--- a/spectree/plugins/starlette_plugin.py
+++ b/spectree/plugins/starlette_plugin.py
@@ -36,15 +36,13 @@ def __init__(self, spectree):
         self.conv2type = {conv: typ for typ, conv in CONVERTOR_TYPES.items()}
 
     def register_route(self, app):
-        self.app = app
-
-        self.app.add_route(
+        app.add_route(
             self.config.spec_url,
             lambda request: JSONResponse(self.spectree.spec),
         )
 
         for ui in self.config.page_templates:
-            self.app.add_route(
+            app.add_route(
                 f"/{self.config.path}/{ui}",
                 lambda request, ui=ui: HTMLResponse(
                     self.config.page_templates[ui].format(
@@ -177,7 +175,7 @@ def parse_route(app, prefix=""):
                 else:
                     parse_route(route, prefix=f"{prefix}{route.path}")
 
-        parse_route(self.app)
+        parse_route(self.spectree.app)
         return routes
 
     def bypass(self, func, method):
diff --git a/spectree/spec.py b/spectree/spec.py
index af43207c..fc0a172c 100644
--- a/spectree/spec.py
+++ b/spectree/spec.py
@@ -99,8 +99,6 @@ def register(self, app: Any):
         self.app = app
         if self.publish_apidoc:
             self.backend.register_route(self.app)
-        else:
-            self.backend.app = self.app
 
     @property
     def spec(self):