diff --git a/board/TencentOS_tiny_EVB_MX/BSP/Hardware/E53_IA1/E53_IA1.c b/board/TencentOS_tiny_EVB_MX/BSP/Hardware/E53_IA1/E53_IA1.c
index 00415d6e..01882a75 100644
--- a/board/TencentOS_tiny_EVB_MX/BSP/Hardware/E53_IA1/E53_IA1.c
+++ b/board/TencentOS_tiny_EVB_MX/BSP/Hardware/E53_IA1/E53_IA1.c
@@ -91,7 +91,7 @@ uint8_t SHT3x_CheckCrc(char data[], char nbrOfBytes, char checksum)
 	
     char crc = 0xFF;
     char bit = 0;
-    char byteCtr ;
+    unsigned char byteCtr;
 	
     //calculates 8-Bit checksum with given polynomial
     for(byteCtr = 0; byteCtr < nbrOfBytes; ++byteCtr)