diff --git a/services/web/app/coffee/Features/Collaborators/CollaboratorsHandler.coffee b/services/web/app/coffee/Features/Collaborators/CollaboratorsHandler.coffee
index 63bd5e785c..889fdf17df 100644
--- a/services/web/app/coffee/Features/Collaborators/CollaboratorsHandler.coffee
+++ b/services/web/app/coffee/Features/Collaborators/CollaboratorsHandler.coffee
@@ -215,7 +215,8 @@ module.exports = CollaboratorsHandler =
 			else
 				return callback(new Error("unknown privilegeLevel: #{privilegeLevel}"))
 
-			ContactManager.addContact adding_user_id, user_id
+			if adding_user_id
+				ContactManager.addContact adding_user_id, user_id
 
 			Project.update { _id: project_id }, { $addToSet: level }, (error) ->
 				return callback(error) if error?
diff --git a/services/web/test/unit/coffee/Collaborators/CollaboratorsHandlerTests.coffee b/services/web/test/unit/coffee/Collaborators/CollaboratorsHandlerTests.coffee
index cb1b5f3dc3..4a2c33a2aa 100644
--- a/services/web/test/unit/coffee/Collaborators/CollaboratorsHandlerTests.coffee
+++ b/services/web/test/unit/coffee/Collaborators/CollaboratorsHandlerTests.coffee
@@ -322,6 +322,13 @@ describe "CollaboratorsHandler", ->
 			it "should not add the user again", ->
 				@Project.update.called.should.equal false
 
+		describe "with null adding_user_id", ->
+			beforeEach ->
+				@CollaboratorHandler.addUserIdToProject @project_id, null, @user_id, "readAndWrite", @callback
+
+			it "should not add the adding user as a contact", ->
+				@ContactManager.addContact.called.should.equal(false)
+
 	describe "removeUserFromAllProjects", ->
 		beforeEach (done) ->
 			@CollaboratorHandler.getProjectsUserIsMemberOf = sinon.stub()