diff --git a/drawers/src/main.cpp b/drawers/src/main.cpp
index 9d93f7a..68c44d4 100644
--- a/drawers/src/main.cpp
+++ b/drawers/src/main.cpp
@@ -3,9 +3,12 @@
 
 const uint8_t I2C_ADDR = 0x10;
 
-const uint8_t CMD_POWER_OFF    = 0x01;
-const uint8_t CMD_LIGHT_INDEX  = 0x02;
-const uint8_t CMD_DRAWER_INDEX = 0x03;
+const uint8_t BITMASK_CMD = 0b00011000;
+const uint8_t BITMASK_PAYLOAD = 0b00000111;
+
+const uint8_t CMD_POWER_OFF    = 0b00001000;
+const uint8_t CMD_LIGHT_INDEX  = 0b00010000;
+const uint8_t CMD_DRAWER_INDEX = 0b00011000;
 
 struct Schublade {
   int schlossPin;
@@ -47,22 +50,20 @@ void openLock(uint8_t indexOn) {
 
 void onI2CReceive(int len) {
   while (Wire.available()) {
-    uint8_t cmd = Wire.read();
+    uint8_t data = Wire.read();
 
-    switch (cmd) {
+    switch (data & BITMASK_CMD) {
 
       case CMD_POWER_OFF:
         turnAllLedsOf();
         break;
 
       case CMD_LIGHT_INDEX:
-        uint8_t lightIndex = Wire.read();
-        turnOnSingleLed(lightIndex);
+        turnOnSingleLed(data & BITMASK_PAYLOAD);
         break;
 
       case CMD_DRAWER_INDEX:
-        uint8_t drawerIndex = Wire.read();
-        openLock(drawerIndex);
+        openLock(data & BITMASK_PAYLOAD);
         break;
     }
   }