diff --git a/lib/legacy/legacy-element-mixin.html b/lib/legacy/legacy-element-mixin.html
index 665b70c064..958dc49aad 100644
--- a/lib/legacy/legacy-element-mixin.html
+++ b/lib/legacy/legacy-element-mixin.html
@@ -937,7 +937,7 @@
        */
       _logger(level, args) {
         // accept ['foo', 'bar'] and [['foo', 'bar']]
-        if (Array.isArray(args) && args.length === 1) {
+        if (Array.isArray(args) && args.length === 1, && Array.isArray(args[0])) {
           args = args[0];
         }
         switch(level) {