diff --git a/src/http.cpp b/src/http.cpp
index 49a3075..b6916bb 100644
--- a/src/http.cpp
+++ b/src/http.cpp
@@ -48,14 +48,20 @@ const Request http::parse_request(const string &request)
             answer = get_parameter(request, "s");
             if (!answer.empty())
             {
-                size = static_cast<uint16_t>(std::stoul(answer));
+                try
+                {
+                    size = static_cast<uint16_t>(std::stoul(answer));
+                } catch (const std::exception &) {}
             }
             else
             {
                 answer = get_parameter(request, "size");
                 if (!answer.empty())
                 {
-                    size = static_cast<uint16_t>(std::stoul(answer));
+                    try
+                    {
+                        size = static_cast<uint16_t>(std::stoul(answer));
+                    } catch (const std::exception &) {}
                 }
             }
             if (size > 512)