diff --git a/cube/User/Src/configCmds.c b/cube/User/Src/configCmds.c
index 60d29cd..6cb8233 100644
--- a/cube/User/Src/configCmds.c
+++ b/cube/User/Src/configCmds.c
@@ -221,6 +221,13 @@ static bool changeDeviceCmd(uint8_t argc, char **args) {
         return makeDevice(0, argc, args, NULL);
     }
 
+    long int rawIndex = strtol(args[1], NULL, 10);
+    if (rawIndex < 0 || rawIndex > getConfig()->numOfDeviceBlocks) {
+        sendFormatString("illegal index, must be greater 0 and less %d\n\r", getConfig()->numOfDeviceBlocks);
+        return false;
+    }
+    uint8_t index = (uint8_t) rawIndex;
+
     t_deviceBlock deviceBlock;
     uint8_t index;
     bool retCode = makeDevice(1, argc, args, &deviceBlock);