diff --git a/lib/mediainfo.rb b/lib/mediainfo.rb
index 14eae9c..5e752b2 100644
--- a/lib/mediainfo.rb
+++ b/lib/mediainfo.rb
@@ -112,6 +112,7 @@ def self.from_uri(input)
 
   def self.set_singleton_method(object,name,parameters)
     # Handle parameters with invalid characters (instance_variable_set throws error)
+    name = name.dup
     name.gsub!('.','_') if name.include?('.') ## period in name
     name.downcase!
     # Create singleton_method