diff --git a/YSFRX.cpp b/YSFRX.cpp
index d343ef5..bfe82d4 100644
--- a/YSFRX.cpp
+++ b/YSFRX.cpp
@@ -27,9 +27,10 @@ const unsigned int BUFFER_LENGTH = 200U;
 
 const q15_t SCALING_FACTOR = 19505;      // Q15(0.60)
 
-const uint32_t PLLMAX = 0x10000U;
-const uint32_t PLLINC = PLLMAX / YSF_RADIO_SYMBOL_LENGTH;
-const uint32_t INC    = PLLINC / 32U;
+const uint32_t PLLMAX     = 0x10000U;
+const uint32_t PLLINC     = PLLMAX / YSF_RADIO_SYMBOL_LENGTH;
+const uint32_t INC_UNLOCK = PLLINC / 32U;
+const uint32_t INC_LOCK   = PLLINC / 64U;
 
 const uint8_t SYNC_SYMBOL_ERRS = 2U;
 const uint8_t SYNC_BIT_ERRS    = 4U;
@@ -311,6 +312,7 @@ static const unsigned short CCITT_TABLE[] = {
 CYSFRX::CYSFRX() :
 m_pll(0U),
 m_prev(false),
+m_inc(INC_UNLOCK),
 m_state(YSFRXS_NONE),
 m_bitBuffer(0x00U),
 m_symbols(),
@@ -335,6 +337,7 @@ void CYSFRX::reset()
 {
   m_pll       = 0U;
   m_prev      = false;
+  m_inc       = INC_UNLOCK;
   m_state     = YSFRXS_NONE;
   m_bitBuffer = 0x00U;
   m_bufferPtr = 0U;
@@ -351,9 +354,9 @@ void CYSFRX::samples(const q15_t* samples, uint8_t length)
 
     if (bit != m_prev) {
       if (m_pll < (PLLMAX / 2U))
-        m_pll += INC;
+        m_pll += m_inc;
       else
-        m_pll -= INC;
+        m_pll -= m_inc;
     }
 
     m_prev = bit;
@@ -440,7 +443,7 @@ void CYSFRX::processNone(q15_t sample)
       m_lostCount = MAX_SYNC_FRAMES;
       m_bufferPtr = YSF_SYNC_LENGTH_BITS;
       m_state     = YSFRXS_DATA;
-      io.setDecode(true);
+      locked(true);
     }
   }
 
@@ -506,7 +509,7 @@ void CYSFRX::processData(q15_t sample)
     m_lostCount--;
     if (m_lostCount == 0U) {
       DEBUG1("YSFRX: sync timed out, lost lock");
-      io.setDecode(false);
+      locked(false);
 
       serial.writeYSFLost();
 
@@ -531,7 +534,7 @@ void CYSFRX::processData(q15_t sample)
 
       if (ok && (FICH[0U] & 0xC0U) == 0x80U) {
         DEBUG1("YSFRX: end of transmission");
-        io.setDecode(false);
+        locked(false);
         m_state = YSFRXS_NONE;
       } else {
         // Start the next frame
@@ -696,3 +699,10 @@ bool CYSFRX::checksum(const uint8_t* fich) const
   return crc8[0U] == fich[5U] && crc8[1U] == fich[4U];
 }
 
+void CYSFRX::locked(bool lock)
+{
+  io.setDecode(lock);
+
+  m_inc = lock ? INC_LOCK : INC_UNLOCK;
+}
+
diff --git a/YSFRX.h b/YSFRX.h
index 46950c0..cf2e172 100644
--- a/YSFRX.h
+++ b/YSFRX.h
@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -38,6 +38,7 @@ public:
 private:
   uint32_t    m_pll;
   bool        m_prev;
+  uint32_t    m_inc;
   YSFRX_STATE m_state;
   uint32_t    m_symbolBuffer;
   uint64_t    m_bitBuffer;
@@ -64,6 +65,7 @@ private:
   uint32_t getSyndrome23127(uint32_t pattern) const;
   uint32_t golay24128(const uint8_t* bytes) const;
   bool checksum(const uint8_t* fich) const;
+  void locked(bool lock);
 };
 
 #endif