diff --git a/gns3server/web/web_server.py b/gns3server/web/web_server.py
index af65496e..8e565cd8 100644
--- a/gns3server/web/web_server.py
+++ b/gns3server/web/web_server.py
@@ -44,7 +44,7 @@ import logging
 log = logging.getLogger(__name__)
 
 if not aiohttp.__version__.startswith("1.3"):
-    raise RuntimeError("You need aiohttp 13 for running GNS3")
+    raise RuntimeError("You need aiohttp 1.3 for running GNS3")
 
 
 class WebServer: