diff --git a/lib/measure-loader/mat_measure_files.rb b/lib/measure-loader/mat_measure_files.rb
index 4073f1fd..1dc28888 100644
--- a/lib/measure-loader/mat_measure_files.rb
+++ b/lib/measure-loader/mat_measure_files.rb
@@ -53,7 +53,7 @@ class << self
 
       def unzip_measure_zip_into_hash(zip_file)
         folders = Hash.new { |h, k| h[k] = {files: []} }
-        Zip::File.open zip_file do |file|
+        Zip::File.open zip_file.path do |file|
           file.each do |f|
             pn = Pathname(f.name)
             next if '__MACOSX'.in? pn.each_filename  # ignore anything in a __MACOSX folder