diff --git a/lib/filter/init.rb b/lib/filter/init.rb
index 23f9b8ee0..93fc56065 100644
--- a/lib/filter/init.rb
+++ b/lib/filter/init.rb
@@ -30,6 +30,7 @@ module BeEF
     def self.is_valid_browserversion?(str)
       return false if not BeEF::Filter.is_non_empty_string?(str)
       return false if BeEF::Filter.has_non_printable_char?(str)  
+      return true if str.eql? "UNKNOWN"
       return false if not BeEF::Filter.nums_only?(str) and not BeEF::Filter.is_valid_float?(str)  
       return false if str.length > 10      
       true