diff --git a/backend/internal/square/square_dev.go b/backend/internal/square/square_dev.go
index 33013ff..a2979df 100644
--- a/backend/internal/square/square_dev.go
+++ b/backend/internal/square/square_dev.go
@@ -161,9 +161,9 @@ func (m *MockClient) GetCheckout(ctx context.Context, checkoutID string) (*Payme
 	log.Printf("[SQUARE-MOCK] GetCheckout: id=%s", checkoutID)
 
 	m.mu.RLock()
-	checkout, ok := m.checkouts[checkoutID]
-	m.mu.RUnlock()
+	defer m.mu.RUnlock()
 
+	checkout, ok := m.checkouts[checkoutID]
 	if !ok {
 		return nil, fmt.Errorf("checkout not found: %s", checkoutID)
 	}
@@ -172,10 +172,7 @@ func (m *MockClient) GetCheckout(ctx context.Context, checkoutID string) (*Payme
 		return nil, fmt.Errorf("checkout pending")
 	}
 
-	m.mu.RLock()
 	result, ok := m.completed[checkoutID]
-	m.mu.RUnlock()
-
 	if !ok {
 		return nil, fmt.Errorf("checkout result not found: %s", checkoutID)
 	}