diff --git a/src/filters/BasePSRFilter.php b/src/filters/BasePSRFilter.php
index 3a0c59d..90f8f28 100644
--- a/src/filters/BasePSRFilter.php
+++ b/src/filters/BasePSRFilter.php
@@ -36,7 +36,7 @@ public function getAutoloadMap(): AutoloadMap {
       (new Map($this->source->getAutoloadMap()['class']))
       ->filterWithKey(
         function(string $class_name, string $file): bool {
-          if (stripos($class_name, $this->prefix) !== 0) {
+          if ($this->prefix !== '' && stripos($class_name, $this->prefix) !== 0) {
             return false;
           }
           $expected = static::getExpectedPathWithoutExtension(