diff --git a/src/MaterializedPath/TreeBuilder.php b/src/MaterializedPath/TreeBuilder.php
index 7a25d41..0356e28 100644
--- a/src/MaterializedPath/TreeBuilder.php
+++ b/src/MaterializedPath/TreeBuilder.php
@@ -71,7 +71,7 @@ public static function fixed(int $levelWidth, callable $accessor): callable
     {
         return function (mixed $data) use ($levelWidth, $accessor): array {
             $path = $accessor($data);
-            if (null === $path) {
+            if (null === $path || $path === '') {
                 return [];
             }
             if (!is_string($path)) {
diff --git a/tests/mptree.phpt b/tests/mptree.phpt
index c2204e9..04aeb56 100644
--- a/tests/mptree.phpt
+++ b/tests/mptree.phpt
@@ -86,6 +86,7 @@ class Item
     );
     Assert::same(['000', '000'], $vectorExtractor('000000'));
     Assert::same(['foo', 'bar'], $vectorExtractor('foobar'));
+    Assert::same(['x'], $vectorExtractor('x')); // shorter than 3
     Assert::same([], $vectorExtractor(''));
     Assert::same([], $vectorExtractor(null));
     Assert::throws(function () use ($vectorExtractor) {