diff --git a/app/services/slash_commands/interpret_service.rb b/app/services/slash_commands/interpret_service.rb
index 78a6e072f26..a7e13648b54 100644
--- a/app/services/slash_commands/interpret_service.rb
+++ b/app/services/slash_commands/interpret_service.rb
@@ -91,41 +91,35 @@ module SlashCommands
     end
 
     desc 'Assign'
-    explanation do |user|
-      "Assigns #{user.to_reference}." if user
+    explanation do |users|
+      "Assigns #{users.map(&:to_reference).to_sentence}." if users.any?
     end
     params '@user'
     condition do
       current_user.can?(:"admin_#{issuable.to_ability_name}", project)
     end
-<<<<<<< HEAD
-    command :assign do |assignee_param|
-      user_ids = extract_references(assignee_param, :user).map(&:id)
+    parse_params do |assignee_param|
+      users = extract_references(assignee_param, :user)
 
-      if user_ids.empty?
-        user_ids = User.where(username: assignee_param.split(' ').map(&:strip)).pluck(:id)
+      if users.empty?
+        users = User.where(username: assignee_param.split(' ').map(&:strip))
       end
 
-      next if user_ids.empty?
+      users
+    end
+    command :assign do |users|
+      next if users.empty?
 
       if issuable.is_a?(Issue)
-        @updates[:assignee_ids] = user_ids
+        @updates[:assignee_ids] = users.map(&:id)
       else
-        @updates[:assignee_id] = user_ids.last
+        @updates[:assignee_id] = users.last.id
       end
-=======
-    parse_params do |assignee_param|
-      extract_references(assignee_param, :user).first ||
-        User.find_by(username: assignee_param)
-    end
-    command :assign do |user|
-      @updates[:assignee_id] = user.id if user
->>>>>>> 10c1bf2d77fd0ab21309d0b136cbc0ac11f56c77
     end
 
     desc 'Remove assignee'
     explanation do
-      "Removes assignee #{issuable.assignee.to_reference}."
+      "Removes assignee #{issuable.assignees.first.to_reference}."
     end
     condition do
       issuable.persisted? &&
diff --git a/spec/services/slash_commands/interpret_service_spec.rb b/spec/services/slash_commands/interpret_service_spec.rb
index 24f2c1407aa..e5e400ee281 100644
--- a/spec/services/slash_commands/interpret_service_spec.rb
+++ b/spec/services/slash_commands/interpret_service_spec.rb
@@ -874,7 +874,7 @@ describe SlashCommands::InterpretService, services: true do
 
     describe 'unassign command' do
       let(:content) { '/unassign' }
-      let(:issue) { create(:issue, project: project, assignee: developer) }
+      let(:issue) { create(:issue, project: project, assignees: [developer]) }
 
       it 'includes current assignee reference' do
         _, explanations = service.explain(content, issue)