diff --git a/app/controllers/exercises_controller.rb b/app/controllers/exercises_controller.rb
index 4e08366c..cc11c72b 100644
--- a/app/controllers/exercises_controller.rb
+++ b/app/controllers/exercises_controller.rb
@@ -219,7 +219,7 @@ class ExercisesController < ApplicationController
             file_params[:content] = nil
             file_params[:native_file] = file_attributes[:content]
           else
-            file_params[:content] = file_attributes[:content].read
+            file_params[:content] = file_attributes[:content].read.encode.delete("\x00")
           end
         end
       end