diff --git a/app/controllers/imports_controller.rb b/app/controllers/imports_controller.rb
index 9431ca098..a5248dc1e 100644
--- a/app/controllers/imports_controller.rb
+++ b/app/controllers/imports_controller.rb
@@ -173,7 +173,7 @@ class ImportsController < ApplicationController
     return if @import.settings['encoding'].blank?
 
     mappings = @import.settings['mapping'] ||= {}
-    headers = @import.headers.map(&:downcase)
+    headers = @import.headers.map{|header| header.to_s.downcase}
 
     # Core fields
     import_type::AUTO_MAPPABLE_FIELDS.each do |field_nm, label_nm|
diff --git a/test/fixtures/files/import_issues_auto_mapping.csv b/test/fixtures/files/import_issues_auto_mapping.csv
index 49785f7a4..17e5c6c2c 100644
--- a/test/fixtures/files/import_issues_auto_mapping.csv
+++ b/test/fixtures/files/import_issues_auto_mapping.csv
@@ -1,2 +1,2 @@
-priority;Subject;start_date;parent;private;progress;custom;"target version";category;user;estimated_hours;tracker;status;database;cf_6
-High;First;2015-07-08;;no;;PostgreSQL;;New category;dlopper;1;bug;new;"PostgreSQL, Oracle";2
+priority;Subject;start_date;parent;private;progress;custom;"target version";category;user;estimated_hours;tracker;status;database;cf_6;
+High;First;2015-07-08;;no;;PostgreSQL;;New category;dlopper;1;bug;new;"PostgreSQL, Oracle";2;"Column with blank header"