--- a/toolkit/components/downloads/ApplicationReputation.cpp
+++ b/toolkit/components/downloads/ApplicationReputation.cpp
@@ -665,16 +665,19 @@ static const char16_t* const kBinaryFile
     //u".workflow", // Mac Automator
     //u".wrc", // FreeArc archive
     u".ws", // Windows script
     u".wsc", // Windows script
     u".wsf", // Windows script
     u".wsh", // Windows script
     u".xar", // MS Excel
     u".xbap", // XAML Browser Application
+    u".xhtml",
+    u".xhtm",
+    u".xht",
     u".xip", // Mac archive
     //u".xlsm", // MS Excel
     //u".xlsx", // MS Excel
     //u".xltm", // MS Excel
     //u".xltx", // MS Excel
     u".xml",
     u".xnk", // MS Exchange
     u".xrm-ms", // Windows