diff --git a/src/am2315/am2315.cpp b/src/am2315/am2315.cpp
index c687cc7d..2e244881 100644
--- a/src/am2315/am2315.cpp
+++ b/src/am2315/am2315.cpp
@@ -233,7 +233,8 @@ AM2315::i2cWriteReg(uint8_t reg, uint8_t* data, uint8_t ilen)
 uint8_t
 AM2315::i2cReadReg(int reg, uint8_t* data, int ilen)
 {
-    uint8_t tdata[16] = { AM2315_READ, reg, ilen };
+  uint8_t tdata[16] = { AM2315_READ, static_cast<uint8_t>(reg),
+                        static_cast<uint8_t>(ilen) };
 
     mraa_result_t ret = mraa_i2c_address(m_i2ControlCtx, m_controlAddr);
     int iLoops = 5;