diff --git a/left/src/slave_protocol_handler.c b/left/src/slave_protocol_handler.c
index 9cc71de..e8719ea 100644
--- a/left/src/slave_protocol_handler.c
+++ b/left/src/slave_protocol_handler.c
@@ -33,9 +33,8 @@ void SlaveProtocolHandler(void)
     uint8_t commandId = SlaveRxBuffer[0];
     switch (commandId) {
         case SlaveCommand_GetKeyStates:
-            SlaveTxSize = KEYBOARD_MATRIX_COLS_NUM*KEYBOARD_MATRIX_ROWS_NUM;
-            BoolBytesToBits(keyMatrix.keyStates, SlaveTxBuffer, SlaveTxSize);
-//            memcpy(SlaveTxBuffer, keyMatrix.keyStates, SlaveTxSize);
+            SlaveTxSize = KEY_STATE_BUFFER_SIZE;
+            BoolBytesToBits(keyMatrix.keyStates, SlaveTxBuffer, LEFT_KEYBOARD_HALF_KEY_COUNT);
             break;
         case SlaveCommand_SetTestLed:
             SlaveTxSize = 0;
diff --git a/left/src/slave_protocol_handler.h b/left/src/slave_protocol_handler.h
index b773c23..d62519f 100644
--- a/left/src/slave_protocol_handler.h
+++ b/left/src/slave_protocol_handler.h
@@ -13,6 +13,9 @@
     #define PROTOCOL_RESPONSE_SUCCESS       0
     #define PROTOCOL_RESPONSE_GENERIC_ERROR 1
 
+    #define LEFT_KEYBOARD_HALF_KEY_COUNT (KEYBOARD_MATRIX_COLS_NUM*KEYBOARD_MATRIX_ROWS_NUM)
+    #define KEY_STATE_BUFFER_SIZE (LEFT_KEYBOARD_HALF_KEY_COUNT/8 + 1)
+
 // Variables:
 
     uint8_t SlaveRxBuffer[SLAVE_RX_BUFFER_SIZE];