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diff --git a/docs/expander-MCP23017.md b/docs/expander-MCP23017.md
index eb562d3e5..f3ff048f3 100644
--- a/docs/expander-MCP23017.md
+++ b/docs/expander-MCP23017.md
@@ -5,7 +5,7 @@
 <!--remove-end-->
 
 
-Using an MCP23017 Expander as a Virtual Board (16 Pin Digital IO)
+Using an MCP23017 Expander as a Virtual Board (16 Pin Digital IO). Pins 15-17 are used to set the I2C hardware address. By default, these pins must be connected to ground. See page eight of the [data sheet](http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf)
 
 
 
diff --git a/tpl/programs.json b/tpl/programs.json
index 09b85bd9f..6e2a9cb6b 100644
--- a/tpl/programs.json
+++ b/tpl/programs.json
@@ -46,7 +46,7 @@
       {
         "file": "expander-MCP23017.js",
         "title": "Expander - MCP23017",
-        "description": "Using an MCP23017 Expander as a Virtual Board (16 Pin Digital IO)"
+        "description": "Using an MCP23017 Expander as a Virtual Board (16 Pin Digital IO). Pins 15-17 are used to set the I2C hardware address. By default, these pins must be connected to ground. See page eight of the [data sheet](http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf)"
       },
       {
         "file": "expander-MCP23008.js",