diff --git a/actionpack/lib/action_view/helpers/asset_tag_helper.rb b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
index a3b99327ce..6d2c28f969 100644
--- a/actionpack/lib/action_view/helpers/asset_tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
@@ -505,8 +505,8 @@ module ActionView
       def image_tag(source, options = {})
         options.symbolize_keys!
 
-        options[:src] = path_to_image(source)
-        options[:alt] ||= File.basename(options[:src], '.*').split('.').first.to_s.capitalize
+        src = options[:src] = path_to_image(source)
+        options[:alt]     ||= File.basename(src, '.*').split('.').first.to_s.capitalize
 
         if size = options.delete(:size)
           options[:width], options[:height] = size.split("x") if size =~ %r{^\d+x\d+$}
@@ -514,7 +514,7 @@ module ActionView
 
         if mouseover = options.delete(:mouseover)
           options[:onmouseover] = "this.src='#{image_path(mouseover)}'"
-          options[:onmouseout]  = "this.src='#{image_path(options[:src])}'"
+          options[:onmouseout]  = "this.src='#{src}'"
         end
 
         tag("img", options)