diff --git a/doc/configuration.rst b/doc/configuration.rst
index f7c40605f..4faf746d9 100644
--- a/doc/configuration.rst
+++ b/doc/configuration.rst
@@ -303,7 +303,7 @@ hub.
 
    YKUSHPowerPort:
      serial: 'YK12345'
-     index: 1
+     index: '1'
 
 The example describes port 1 on the YKUSH USB hub with the
 serial ``YK12345``.
@@ -311,7 +311,8 @@ Use ``ykushcmd -l`` to get your serial number.
 
 Arguments:
   - serial (str): serial number of the YKUSH hub
-  - index (int): number of the port to switch
+  - index (str): number of the port to switch, use ``a`` to control the whole hub as one logical
+    port
 
 Used by:
   - `YKUSHPowerDriver`_
diff --git a/labgrid/resource/ykushpowerport.py b/labgrid/resource/ykushpowerport.py
index b7a967816..be3b9c04f 100644
--- a/labgrid/resource/ykushpowerport.py
+++ b/labgrid/resource/ykushpowerport.py
@@ -11,10 +11,10 @@ class YKUSHPowerPort(Resource):
 
     Args:
         serial (str): serial of the YKUSH device
-        index (int): port index"""
+        index (str): port index"""
     serial = attr.ib(validator=attr.validators.instance_of(str))
-    index = attr.ib(validator=attr.validators.instance_of(int),
-                    converter=int)
+    index = attr.ib(validator=attr.validators.instance_of(str),
+                    converter=str)
 
 @target_factory.reg_resource
 @attr.s(eq=False)
@@ -23,7 +23,7 @@ class NetworkYKUSHPowerPort(NetworkResource):
 
     Args:
         serial (str): serial of the YKUSH device
-        index (int): port index"""
+        index (str): port index"""
     serial = attr.ib(validator=attr.validators.instance_of(str))
-    index = attr.ib(validator=attr.validators.instance_of(int),
-                    converter=int)
+    index = attr.ib(validator=attr.validators.instance_of(str),
+                    converter=str)