diff --git a/sonoff/_releasenotes.ino b/sonoff/_releasenotes.ino
index 034877a45..72b5f1901 100644
--- a/sonoff/_releasenotes.ino
+++ b/sonoff/_releasenotes.ino
@@ -3,6 +3,7 @@
  * Add random window to timers (#2447)
  * Add optional KNX IP Protocol Support (#2402)
  * Fix compile error when using ESP/Arduino library v2.3.0 by reverting KNX async UDP library to default UDP library (#2488,#2492,#2493)
+ * Fix configuration filename truncation when it contains spaces (#2484, #2490)
  *
  * 5.12.0l
  * Release rules up to 511 characters
diff --git a/sonoff/webserver.ino b/sonoff/webserver.ino
index 38198826e..b1e322648 100644
--- a/sonoff/webserver.ino
+++ b/sonoff/webserver.ino
@@ -1001,7 +1001,7 @@ void HandleBackupConfiguration()
   WebServer->setContentLength(sizeof(buffer));
 
   char attachment[100];
-  snprintf_P(attachment, sizeof(attachment), PSTR("attachment; filename=Config_%s_%s.dmp"), Settings.friendlyname[0], my_version);
+  snprintf_P(attachment, sizeof(attachment), PSTR("attachment; filename=Config_%s_%s.dmp"), SpaceToUnderscore(Settings.friendlyname[0]), my_version);
   WebServer->sendHeader(F("Content-Disposition"), attachment);
   WebServer->send(200, FPSTR(HDR_CTYPE_STREAM), "");
   memcpy(buffer, &Settings, sizeof(buffer));