diff --git a/stk500v2/main.cpp b/stk500v2/main.cpp
index cab4170..77fbeec 100644
--- a/stk500v2/main.cpp
+++ b/stk500v2/main.cpp
@@ -321,13 +321,15 @@ static inline void formatLoadAddressAnswer(Message &msg)
 
 static inline void formatReadFlashIspAnswer(Message &msg, uint32_t &addr)
 {
+	const uint16_t byteAddress = 2 * addr;
 	const uint16_t numBytes = static_cast<uint16_t>(msg.body[1]) << 8 | msg.body[2];
 	msg.size = 3 + numBytes;
 	msg.body[1] = STATUS_CMD_OK;
 	for (uint16_t i = 0; i < numBytes; ++i) {
-		msg.body[i + 2] = pgm_read_byte(static_cast<uint16_t>(addr + i));
+		msg.body[i + 2] = pgm_read_byte(static_cast<uint16_t>(byteAddress + i));
 	}
-	addr += numBytes;
+	const auto numWords = numBytes / 2;
+	addr += numWords;
 	msg.body[numBytes + 2] = STATUS_CMD_OK;
 
 	msg.checksum = calcChecksum(msg);
@@ -459,10 +461,12 @@ static inline void formatReadEepromIspAnswer(Message &msg, uint32_t &addr)
 
 static inline void formatProgramFlashIspAnswer(Message &msg, uint32_t &addr)
 {
-	if (addr < getFlashSize())
-		writeFlashPage(addr, msg.body + 10);
+	const auto byteAddress = 2 * addr;
+	if (byteAddress < getFlashSize())
+		writeFlashPage(byteAddress, msg.body + 10);
 	const uint16_t numBytes = static_cast<uint16_t>(msg.body[1]) << 8 | msg.body[2];
-	addr += numBytes;
+	const auto numWords = numBytes / 2;
+	addr += numWords;
 
 	msg.size = 2;
 	msg.body[1] = STATUS_CMD_OK;