diff --git a/app/models/user.rb b/app/models/user.rb
index cc4f38a9e7b..1bde1ea1b8d 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -1061,6 +1061,8 @@ class User < ActiveRecord::Base
 
   # Delete unactivated accounts (without verified email) that are over a week old
   def self.purge_unactivated
+    return [] if SiteSetting.purge_unactivated_users_grace_period_days <= 0
+
     to_destroy = User.where(active: false)
       .joins('INNER JOIN user_stats AS us ON us.user_id = users.id')
       .where("created_at < ?", SiteSetting.purge_unactivated_users_grace_period_days.days.ago)
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 11b04322a91..6e098af27a4 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -1192,7 +1192,7 @@ en:
     clean_up_uploads: "Remove orphan unreferenced uploads to prevent illegal hosting. WARNING: you may want to back up of your /uploads directory before enabling this setting."
     clean_orphan_uploads_grace_period_hours: "Grace period (in hours) before an orphan upload is removed."
     purge_deleted_uploads_grace_period_days: "Grace period (in days) before a deleted upload is erased."
-    purge_unactivated_users_grace_period_days: "Grace period (in days) before a user who has not activated their account is deleted."
+    purge_unactivated_users_grace_period_days: "Grace period (in days) before a user who has not activated their account is deleted. Set to 0 to never purge unactivated users."
     enable_s3_uploads: "Place uploads on Amazon S3 storage. IMPORTANT: requires valid S3 credentials (both access key id & secret access key)."
     s3_use_iam_profile: 'Use AWS EC2 IAM role to retrieve keys. NOTE: enabling will override "s3 access key id" and "s3 secret access key" settings.'
     s3_upload_bucket: "The Amazon S3 bucket name that files will be uploaded into. WARNING: must be lowercase, no periods, no underscores."
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index 7fa83a5b3bf..066290194e7 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -1183,6 +1183,15 @@ describe User do
       expect(all_users.include?(inactive)).to eq(true)
       expect(all_users.include?(inactive_old)).to eq(false)
     end
+
+    it "does nothing if purge_unactivated_users_grace_period_days is 0" do
+      SiteSetting.purge_unactivated_users_grace_period_days = 0
+      User.purge_unactivated
+      all_users = User.all
+      expect(all_users.include?(user)).to eq(true)
+      expect(all_users.include?(inactive)).to eq(true)
+      expect(all_users.include?(inactive_old)).to eq(true)
+    end
   end
 
   describe "hash_passwords" do