diff --git a/SerialModem.cpp b/SerialModem.cpp
index add57ff..9b893c8 100644
--- a/SerialModem.cpp
+++ b/SerialModem.cpp
@@ -2031,7 +2031,7 @@ bool CSerialModem::setConfig1()
 	if (m_pocsagEnabled)
 		buffer[4U] |= 0x20U;
 	if (m_m17Enabled)
-		buffer[4U] |= 0x40U;
+		buffer[4U] |= 0x80U;
 
 	buffer[5U] = m_txDelay / 10U;		// In 10ms units