diff --git a/dbus.hpp b/dbus.hpp
index 50dcdfb..f9668c0 100644
--- a/dbus.hpp
+++ b/dbus.hpp
@@ -64,7 +64,7 @@
  *                       services and interfaces.
  */
 DbusSubtree getSubtree(sdbusplus::bus::bus& bus, const std::string& root,
-                       size_t depth, const std::string& interface);
+                       int depth, const std::string& interface);
 
 /**
  * Get the D-Bus service name for the object path and interface from