diff --git a/lib/redmine/core_ext/string/conversions.rb b/lib/redmine/core_ext/string/conversions.rb
index 68fbcde75..0d1d32f58 100644
--- a/lib/redmine/core_ext/string/conversions.rb
+++ b/lib/redmine/core_ext/string/conversions.rb
@@ -36,6 +36,13 @@ module Redmine #:nodoc:
           s.gsub!(',', '.')
           begin; Kernel.Float(s); rescue; nil; end
         end
+        
+        # Object#to_a removed in ruby1.9
+        if RUBY_VERSION > '1.9'
+          def to_a
+            [self.dup]
+          end
+        end
       end
     end
   end