diff --git a/lib/config/validation.js b/lib/config/validation.js
index bdb65f6890cf8c59aa7f4bf9c6207fe946879df7..673fdc6474e2f7a914652dc9053f21c03dad5e6e 100644
--- a/lib/config/validation.js
+++ b/lib/config/validation.js
@@ -96,30 +96,30 @@ function validateConfig(config) {
               depName: 'Configuration Error',
               message: `Configuration option \`${key}\` should be a list (Array)`,
             });
-          } else if (key === 'extends') {
-            for (const subval of val) {
-              if (isString(subval) && subval.match(/^:timezone(.+)$/)) {
-                const [, timezone] = subval.match(/^:timezone\((.+)\)$/);
-                const [validTimezone, errorMessage] = hasValidTimezone(
-                  timezone
-                );
-                if (!validTimezone) {
-                  errors.push({
-                    depName: 'Configuration Error',
-                    message: errorMessage,
-                  });
-                }
-              }
-            }
           } else {
-            // eslint-disable-next-line no-loop-func
-            val.forEach(subval => {
+            for (const subval of val) {
               if (isObject(subval)) {
                 const subValidation = module.exports.validateConfig(subval);
                 warnings = warnings.concat(subValidation.warnings);
                 errors = errors.concat(subValidation.errors);
               }
-            });
+            }
+            if (key === 'extends') {
+              for (const subval of val) {
+                if (isString(subval) && subval.match(/^:timezone(.+)$/)) {
+                  const [, timezone] = subval.match(/^:timezone\((.+)\)$/);
+                  const [validTimezone, errorMessage] = hasValidTimezone(
+                    timezone
+                  );
+                  if (!validTimezone) {
+                    errors.push({
+                      depName: 'Configuration Error',
+                      message: errorMessage,
+                    });
+                  }
+                }
+              }
+            }
           }
         } else if (type === 'string') {
           if (!isString(val)) {