diff --git a/lib/HM330x/HM330x.cpp b/lib/HM330x/HM330x.cpp
index a5269ec..05ae3c1 100644
--- a/lib/HM330x/HM330x.cpp
+++ b/lib/HM330x/HM330x.cpp
@@ -80,7 +80,7 @@ bool HM330x::sendCmd(uint8_t cmd) {
 
 // Calculate CRC8
 uint8_t HM330x::calcSum(uint8_t bytes[]) {
-  uint8_t crc8;
+  uint8_t crc8 = 0;
   for (int i = 0; i < HM330x_DATA_LEN - 1; i++) {
     crc8 += bytes[i];
   }