diff --git a/app/controllers/waiting_lists_controller.rb b/app/controllers/waiting_lists_controller.rb
index 471def73d..a27f0c759 100644
--- a/app/controllers/waiting_lists_controller.rb
+++ b/app/controllers/waiting_lists_controller.rb
@@ -26,7 +26,13 @@ def create # rubocop:disable Metrics/MethodLength
   end
 
   def destroy
-    WaitingList.find_by(invitation_id: @invitation.id).destroy
+    entry = WaitingList.find_by(invitation_id: @invitation.id)
+    unless entry
+      return redirect_to(invitation_path(@invitation),
+                         notice: 'You are not on the waiting list')
+    end
+
+    entry.destroy
     MemberActivityRecorder.record(actor: @invitation.member, key: 'waiting_list.left',
                                   trackable: @invitation)
 
diff --git a/spec/controllers/waiting_lists_controller_spec.rb b/spec/controllers/waiting_lists_controller_spec.rb
index cf09b26c4..047d1fc6f 100644
--- a/spec/controllers/waiting_lists_controller_spec.rb
+++ b/spec/controllers/waiting_lists_controller_spec.rb
@@ -48,6 +48,21 @@
   end
 
   describe 'DELETE #destroy' do
+    context 'when the waiting-list entry is already gone' do
+      it 'redirects with a notice instead of raising' do
+        delete :destroy, params: { invitation_id: invitation.token }
+
+        expect(response).to redirect_to(invitation_path(invitation))
+        expect(flash[:notice]).to eq('You are not on the waiting list')
+      end
+
+      it 'does not record a "waiting_list.left" activity' do
+        delete :destroy, params: { invitation_id: invitation.token }
+
+        expect(PublicActivity::Activity.where(key: 'waiting_list.left')).to be_empty
+      end
+    end
+
     context 'without a CSRF token (browser did not send session cookie)' do
       include_context 'with forgery protection enforced'