diff --git a/packages/webpack-cli/lib/groups/resolveConfig.js b/packages/webpack-cli/lib/groups/resolveConfig.js
index 392ab39393d..1cd89e901a8 100644
--- a/packages/webpack-cli/lib/groups/resolveConfig.js
+++ b/packages/webpack-cli/lib/groups/resolveConfig.js
@@ -175,13 +175,13 @@ const finalize = async (moduleObj, args) => {
             return rawConfig;
         }),
     ).then((allConfigs) => {
-        allConfigs.map((singleConfig) => {
+        for (const singleConfig of allConfigs) {
             if (Array.isArray(singleConfig)) {
-                singleConfig.map((conf) => configs.push(conf));
+                configs.push(...singleConfig);
             } else {
                 configs.push(singleConfig);
             }
-        });
+        }
     });
 
     if (configName) {