diff --git a/packages/server/src/sdk/app/datasources/datasources.ts b/packages/server/src/sdk/app/datasources/datasources.ts
index 25b05e351e..74c2ff7eb0 100644
--- a/packages/server/src/sdk/app/datasources/datasources.ts
+++ b/packages/server/src/sdk/app/datasources/datasources.ts
@@ -135,7 +135,7 @@ export function mergeConfigs(update: Datasource, old: Datasource) {
   // specific to REST datasources, fix the auth configs again if required
   if (hasAuthConfigs(update)) {
     const configs = update.config.authConfigs as RestAuthConfig[]
-    const oldConfigs = old.config?.authConfigs as RestAuthConfig[] || []
+    const oldConfigs = (old.config?.authConfigs as RestAuthConfig[]) || []
     for (let config of configs) {
       if (config.type !== RestAuthType.BASIC) {
         continue