diff --git a/hardware/powermate/README.md b/hardware/powermate/README.md
index efae74b9..3e42dab2 100644
--- a/hardware/powermate/README.md
+++ b/hardware/powermate/README.md
@@ -20,4 +20,15 @@ This node outputs messages for 3 different events
 
 For the first 2 the message payload of 'up' or 'down' respectively is published to the topic + '/button'. For the wheel rotation the message payload is +ve for clockwise and -ve for anti-clockwise on the topic + '/wheel'
 
+Permissions
+-----
+Depending on OS, you may get an error that looks something like 
+
+    cannot open device with path 0001:0004:00
+    
+If this happens, it is likely because your user doesn't have permissions for the PowerMate device. In Linux (specifically Raspbian), creating the file /etc/udev/rules/95-powermate.rules and entering the following text:
+
+    SUBSYSTEM=="usb", ATTRS{idVendor}=="077d", ATTRS{idProduct}=="0410", SYMLINK+="powermate", MODE="660", GROUP="input"
+
+will assign the PowerMate device to the "input" group, which the pi user belongs to. For other OSs, change the GROUP entry to a group that your user belongs to.