diff --git a/src/CliProgram/AutoPrefix/AutoPrefixNamespaceManager.php b/src/CliProgram/AutoPrefix/AutoPrefixNamespaceManager.php
index 134dc2f..1e516e2 100644
--- a/src/CliProgram/AutoPrefix/AutoPrefixNamespaceManager.php
+++ b/src/CliProgram/AutoPrefix/AutoPrefixNamespaceManager.php
@@ -83,7 +83,7 @@ class AutoPrefixNamespaceManager implements IAutoPrefixManager {
         $commandClass = new ReflectionClass($command);
         $commandNamespace = '\\' . $commandClass->getNamespaceName();
 
-        if ($commandNamespace !== $this->getNamespace() && mb_substr($commandNamespace, mb_strlen($this->getNamespace() . '\\')) !== $this->getNamespace() . '\\') {
+        if ($commandNamespace !== $this->getNamespace() && mb_substr($commandNamespace, 0, mb_strlen($this->getNamespace() . '\\')) !== $this->getNamespace() . '\\') {
             return null;
         }
         return implode(