diff --git a/server/main.go b/server/main.go
index df9120b..8c47ba9 100644
--- a/server/main.go
+++ b/server/main.go
@@ -237,12 +237,22 @@ func main() {
 			return c.JSON(http.StatusBadRequest, "missing field 'name'")
 		}
 
+		var target *Client = nil
+
 		for _, client := range clients {
 			if client.ID == id || client.Name == id.String() {
-				client.Name = name
-				client.UpdatedAt = time.Now()
-				return c.JSON(http.StatusOK, echo.Map{"message": "ok"})
+				target = client
 			}
+
+			if client.Name == name {
+				return c.JSON(http.StatusBadRequest, echo.Map{"message": "name already used"})
+			}
+		}
+
+		if target != nil {
+			target.Name = name
+			target.UpdatedAt = time.Now()
+			return c.JSON(http.StatusOK, echo.Map{"message": "ok"})
 		}
 
 		return c.JSON(http.StatusNotFound, echo.Map{"message": "not found"})