diff --git a/src/AttributeRouting/Logging/RouteLoggingInfo.cs b/src/AttributeRouting/Logging/RouteLoggingInfo.cs
index deb104b..744e6e1 100644
--- a/src/AttributeRouting/Logging/RouteLoggingInfo.cs
+++ b/src/AttributeRouting/Logging/RouteLoggingInfo.cs
@@ -40,7 +40,7 @@ public static RouteLoggingInfo GetRouteInfo(string url,
             
             foreach (var @default in allDefaults)
             {
-                var defaultValue = @default.Value.ToString();
+                var defaultValue = (@default.Value ?? string.Empty).ToString();
                 item.Defaults.Add(@default.Key, defaultValue);
             }
 
@@ -144,4 +144,4 @@ public static RouteLoggingInfo GetRouteInfo(string url,
             return item;
         }
     }
-}
\ No newline at end of file
+}