diff --git a/flask_apispec/extension.py b/flask_apispec/extension.py
index 2c6bbb5..5767682 100644
--- a/flask_apispec/extension.py
+++ b/flask_apispec/extension.py
@@ -84,7 +84,22 @@ def add_swagger_routes(self):
 
         self.app.register_blueprint(blueprint)
 
+    def fix_base_path(self):
+        """Lazily set OpenAPI basePath for each request.
+
+        This is to reflect the path root the application is running under.
+        c.f. SCRIPT_NAME https://www.python.org/dev/peps/pep-0333/#environ-variables
+        """
+        if not flask.has_request_context():
+            # not in request
+            return
+        if not flask.request.script_root:
+            # not running under different root
+            return
+        self.spec.options['basePath'] = flask.request.script_root
+
     def swagger_json(self):
+        self.fix_base_path()
         return flask.jsonify(self.spec.to_dict())
 
     def swagger_ui(self):
diff --git a/flask_apispec/utils.py b/flask_apispec/utils.py
index 8c66e35..e6b5a27 100644
--- a/flask_apispec/utils.py
+++ b/flask_apispec/utils.py
@@ -48,11 +48,10 @@ def __init__(self, options=None, inherit=None, apply=None):
 
     def __eq__(self, other):
         if isinstance(other, Annotation):
-            return (
-                self.options == other.options and
-                self.inherit == other.inherit and
+            return self.options == other.options and \
+                self.inherit == other.inherit and \
                 self.apply == other.apply
-            )
+
         return NotImplemented
 
     def __ne__(self, other):
@@ -76,10 +75,9 @@ def merge(self, other):
         )
 
 def resolve_annotations(func, key, parent=None):
-    annotations = (
-        getattr(func, '__apispec__', {}).get(key, []) +
+    annotations = getattr(func, '__apispec__', {}).get(key, []) + \
         getattr(parent, '__apispec__', {}).get(key, [])
-    )
+
     return functools.reduce(
         lambda first, second: first.merge(second),
         [annotation.resolve(parent) for annotation in annotations],