diff --git a/Makefile b/Makefile
index f0001076..841c7dca 100644
--- a/Makefile
+++ b/Makefile
@@ -52,7 +52,7 @@ CFLAGS += -Ilib -Idep/fmt -Iarch
 export OBJDIR = .obj
 
 all: .obj/build.ninja
-	@ninja -f .obj/build.ninja
+	@ninja -f .obj/build.ninja -k 0
 	@if command -v cscope > /dev/null; then cscope -bRq; fi
 
 clean:
diff --git a/arch/ibm/decoder.cc b/arch/ibm/decoder.cc
index 5791d017..4156a4d6 100644
--- a/arch/ibm/decoder.cc
+++ b/arch/ibm/decoder.cc
@@ -108,6 +108,7 @@ public:
 		_currentHeaderLength = (matcher == &MFM_PATTERN) ? 3 : 0;
 
 		Fluxmap::Position here = tell();
+		resetFluxDecoder();
 		if (_currentHeaderLength > 0)
 			readRawBits(_currentHeaderLength*16);
 		auto idbits = readRawBits(16);
diff --git a/lib/decoders/decoders.cc b/lib/decoders/decoders.cc
index 6de123e6..b1f1b21b 100644
--- a/lib/decoders/decoders.cc
+++ b/lib/decoders/decoders.cc
@@ -91,7 +91,7 @@ std::unique_ptr<TrackDataFlux> AbstractDecoder::decodeToSectors(
         /* Read the sector record. */
 
         recordStart = fmr.tell();
-		_decoder.reset(new FluxDecoder(&fmr, _sector->clock, _config));
+		resetFluxDecoder();
         decodeSectorRecord();
         Fluxmap::Position recordEnd = fmr.tell();
         pushRecord(recordStart, recordEnd);
@@ -112,7 +112,7 @@ std::unique_ptr<TrackDataFlux> AbstractDecoder::decodeToSectors(
             recordStart = fmr.tell();
             if (r == DATA_RECORD)
 			{
-				_decoder.reset(new FluxDecoder(&fmr, _sector->clock, _config));
+				resetFluxDecoder();
                 decodeDataRecord();
 			}
             recordEnd = fmr.tell();
@@ -143,6 +143,11 @@ void AbstractDecoder::pushRecord(const Fluxmap::Position& start, const Fluxmap::
     _fmr->seek(here);
 }
 
+void AbstractDecoder::resetFluxDecoder()
+{
+	_decoder.reset(new FluxDecoder(_fmr, _sector->clock, _config));
+}
+
 std::vector<bool> AbstractDecoder::readRawBits(unsigned count)
 {
 	return _decoder->readBits(count);
diff --git a/lib/decoders/decoders.h b/lib/decoders/decoders.h
index 2700093b..44ff3e54 100644
--- a/lib/decoders/decoders.h
+++ b/lib/decoders/decoders.h
@@ -48,8 +48,8 @@ public:
     std::unique_ptr<TrackDataFlux> decodeToSectors(std::shared_ptr<const Fluxmap> fluxmap, unsigned cylinder, unsigned head);
     void pushRecord(const Fluxmap::Position& start, const Fluxmap::Position& end);
 
+	void resetFluxDecoder();
     std::vector<bool> readRawBits(unsigned count);
-    //{ return _fmr->readRawBits(count, _sector->clock); }
 
     Fluxmap::Position tell()
     { return _fmr->tell(); } 
diff --git a/lib/decoders/fluxdecoder.cc b/lib/decoders/fluxdecoder.cc
index 63f47d2d..c5e89603 100644
--- a/lib/decoders/fluxdecoder.cc
+++ b/lib/decoders/fluxdecoder.cc
@@ -14,15 +14,21 @@ FluxDecoder::FluxDecoder(FluxmapReader* fmr, nanoseconds_t bitcell,
 	_clock_centre(bitcell),
 	_clock_min(bitcell * (1.0 - _pll_adjust)),
 	_clock_max(bitcell * (1.0 + _pll_adjust)),
-	_flux(0)
+	_flux(0),
+	_leading_zeroes(fmr->tell().zeroes)
 {}
 
 
 bool FluxDecoder::readBit()
 {
-	if (_first_bit)
+	if (_leading_zeroes > 0)
 	{
-		_first_bit = false;
+		_leading_zeroes--;
+		return false;
+	}
+	else if (_leading_zeroes == 0)
+	{
+		_leading_zeroes--;
 		return true;
 	}