diff --git a/src/output/output_hls.cpp b/src/output/output_hls.cpp
index 443f8e9f..f091dbdb 100644
--- a/src/output/output_hls.cpp
+++ b/src/output/output_hls.cpp
@@ -220,7 +220,14 @@ namespace Mist {
         std::string tmpStr = HTTP_R.getUrl();
         std::string fmtStr = "/hls/" + streamName + "/%u_%u/%llu_%llu.ts";
         long long unsigned int from;
-        sscanf(tmpStr.c_str(), fmtStr.c_str(), &vidTrack, &audTrack, &from, &until);
+        if (sscanf(tmpStr.c_str(), fmtStr.c_str(), &vidTrack, &audTrack, &from, &until) != 4){
+          WARN_MSG("Could not parse URL: %s", HTTP_R.getUrl().c_str());
+          HTTP_S.Clean();
+          HTTP_S.SetBody("The HLS URL wasn't understood - what did you want, exactly?\n");
+          myConn.SendNow(HTTP_S.BuildResponse("404", "URL mismatch"));
+          HTTP_R.Clean(); //clean for any possible next requests
+          continue;
+        }
         DEBUG_MSG(DLVL_DEVEL, "Vid %u, Aud %u, From %llu, Until %llu", vidTrack, audTrack, from, until);
         selectedTracks.clear();
         selectedTracks.insert(vidTrack);