diff --git a/rakefiles/assets.rake b/rakefiles/assets.rake
index c0757b712b..fffd58caf0 100644
--- a/rakefiles/assets.rake
+++ b/rakefiles/assets.rake
@@ -14,7 +14,7 @@ def preprocess_with_mako(filename)
            "print Template(filename=\"#{filename}\")" +
            # Total hack. It works because a Python dict literal has
            # the same format as a JSON object.
-           ".render(env=#{ENV_TOKENS.to_json});"
+           ".render(env=#{ENV_TOKENS.to_json.gsub("true","True").gsub("false","False")});"
 
     # strip off the .mako extension
     output_filename = filename.chomp(File.extname(filename))