diff --git a/Src/modbus_master.c b/Src/modbus_master.c
index c6b6d2c..5d769bf 100644
--- a/Src/modbus_master.c
+++ b/Src/modbus_master.c
@@ -93,7 +93,7 @@ int MB_RespGet_CoilState(RS_MsgTypeDef *modbus_msg, uint16_t coil_addr, int *coi
   if(bit_index < 8)
     *coil_state = (modbus_msg->DATA[data_index] >> (bit_index+8)) & 0x01;
   else
-    *coil_state = ((modbus_msg->DATA[data_index]&0xFF) >> bit_index) & 0x01;
+    *coil_state = ((modbus_msg->DATA[data_index]&0xFF) >> bit_index-8) & 0x01;
     
   
   return 1;