diff --git a/DStarControl.cpp b/DStarControl.cpp
index 6846cfd..75cef55 100644
--- a/DStarControl.cpp
+++ b/DStarControl.cpp
@@ -347,7 +347,7 @@ bool CDStarControl::writeModem(unsigned char *data, unsigned int len)
 
 		// Check for the fast data signature
 		if (m_rfState == RS_RF_AUDIO) {
-			unsigned char slowDataType = data[DSTAR_VOICE_FRAME_LENGTH_BYTES + 1U] & DSTAR_SLOW_DATA_TYPE_MASK;
+			unsigned char slowDataType = (data[DSTAR_VOICE_FRAME_LENGTH_BYTES + 1U] ^ DSTAR_SCRAMBLER_BYTE1) & DSTAR_SLOW_DATA_TYPE_MASK;
 			if (slowDataType == DSTAR_SLOW_DATA_TYPE_FAST_DATA1 || slowDataType == DSTAR_SLOW_DATA_TYPE_FAST_DATA2) {
 				LogMessage("D-Star, switching to fast data mode");
 				m_rfState = RS_RF_DATA;
diff --git a/DStarDefines.h b/DStarDefines.h
index 821a7e2..3f826ac 100644
--- a/DStarDefines.h
+++ b/DStarDefines.h
@@ -67,6 +67,10 @@ const unsigned char DSTAR_ACK_FLAG            = 0x03U;
 const unsigned char DSTAR_NO_RESPONSE         = 0x02U;
 const unsigned char DSTAR_RELAY_UNAVAILABLE   = 0x01U;
 
+const unsigned char DSTAR_SCRAMBLER_BYTE1 = 0x70U;
+const unsigned char DSTAR_SCRAMBLER_BYTE2 = 0x4FU;
+const unsigned char DSTAR_SCRAMBLER_BYTE3 = 0x93U;
+
 const unsigned char DSTAR_SYNC_BYTES[] = {0x55U, 0x2DU, 0x16U};
 
 const unsigned char DSTAR_DTMF_MASK[] = { 0x82U, 0x08U, 0x20U, 0x82U, 0x00U, 0x00U, 0x82U, 0x00U, 0x00U };