diff --git a/CHANGES.rst b/CHANGES.rst
index a68c3a8..3887599 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -2,6 +2,12 @@
  CHANGES
 =========
 
+0.8.0 (XXXX-XX-XX)
+==================
+
+- Resolve ``KeyError`` exception when requesting with an unsupported
+  method (#298)
+
 0.7.0 (2018-03-05)
 ==================
 
diff --git a/aiohttp_cors/cors_config.py b/aiohttp_cors/cors_config.py
index 2e1aeea..c9a58c6 100644
--- a/aiohttp_cors/cors_config.py
+++ b/aiohttp_cors/cors_config.py
@@ -154,7 +154,15 @@ async def _on_response_prepare(self,
 
         # Processing response of non-preflight CORS-enabled request.
 
-        config = self._router_adapter.get_non_preflight_request_config(request)
+        try:
+            config = self._router_adapter.get_non_preflight_request_config(request)
+        except KeyError as e:
+            if response.status == 405 and e.args[0] == "method not supported":
+                # Permit the response if the method is not supported - e.g: when
+                # using a class derived from web.View and CorsViewMixin
+                return
+
+            raise
 
         # Handle according to part 6.1 of the CORS specification.
 
diff --git a/aiohttp_cors/mixin.py b/aiohttp_cors/mixin.py
index f5b4506..d04ccf4 100644
--- a/aiohttp_cors/mixin.py
+++ b/aiohttp_cors/mixin.py
@@ -25,7 +25,7 @@ def get_request_config(cls, request, request_method):
         method = getattr(cls, request_method.lower(), None)
 
         if not method:
-            raise KeyError()
+            raise KeyError("method not supported")
 
         config_property_key = "{}_cors_config".format(request_method.lower())