diff --git a/src/map/IMG/huffmanstream.cpp b/src/map/IMG/huffmanstream.cpp
index 084f6999..f3b8b746 100644
--- a/src/map/IMG/huffmanstream.cpp
+++ b/src/map/IMG/huffmanstream.cpp
@@ -2,7 +2,7 @@
 
 using namespace IMG;
 
-bool HuffmanStreamF::init(bool line)
+bool HuffmanDeltaStreamF::init(bool line)
 {
 	if (line) {
 		if (!(sign(_lonSign) && sign(_latSign)))
@@ -13,7 +13,7 @@ bool HuffmanStreamF::init(bool line)
 	}
 
 	quint32 eb;
-	if (!_bs.read(1, eb))
+	if (!read(1, eb))
 		return false;
 
 	Q_ASSERT(!eb);
@@ -23,7 +23,7 @@ bool HuffmanStreamF::init(bool line)
 	return true;
 }
 
-bool HuffmanStreamR::init()
+bool HuffmanDeltaStreamR::init()
 {
 	if (!(sign(_lonSign) && sign(_latSign)))
 		return false;
@@ -31,13 +31,13 @@ bool HuffmanStreamR::init()
 	return true;
 }
 
-bool HuffmanStreamR::init(int lonSign, int latSign, quint32 data,
-  quint32 dataSize)
+bool HuffmanDeltaStreamR::init(quint32 data, quint32 dataSize)
 {
-	_lonSign = lonSign;
-	_latSign = latSign;
 	_symbolData = data;
 	_symbolDataSize = dataSize;
 
+	if (!(sign(_lonSign) && sign(_latSign)))
+		return false;
+
 	return true;
 }
diff --git a/src/map/IMG/huffmanstream.h b/src/map/IMG/huffmanstream.h
index c1f92e93..0dcc7ea8 100644
--- a/src/map/IMG/huffmanstream.h
+++ b/src/map/IMG/huffmanstream.h
@@ -10,51 +10,24 @@ template <class BitStream>
 class HuffmanStream {
 public:
 	HuffmanStream(BitStream &bitstream, const HuffmanTable &table)
-	  : _bs(bitstream), _table(table), _symbolDataSize(0), _symbolData(0),
-	  _lonSign(0), _latSign(0) {}
+	  : _symbolDataSize(0), _symbolData(0), _bs(bitstream), _table(table) {}
 
 	bool read(int bits, quint32 &val);
 	bool readSymbol(quint32 &symbol);
-	bool readNext(qint32 &lonDelta, qint32 &latDelta)
-	{
-		if (!(readDelta(_lonSign, lonDelta) && readDelta(_latSign, latDelta)))
-			return false;
-
-		return (lonDelta || latDelta);
-	}
 
 	bool atEnd() const
 	  {return _symbolDataSize + _bs.bitsAvailable() < _table.symBits();}
 	bool flush() {return _bs.flush();}
 
 protected:
-	bool sign(int &val);
-	bool readDelta(int sign, qint32 &delta);
-
-	BitStream &_bs;
-	const HuffmanTable &_table;
 	quint32 _symbolDataSize;
 	quint32 _symbolData;
-	int _lonSign, _latSign;
+
+private:
+	BitStream &_bs;
+	const HuffmanTable &_table;
 };
 
-template <class BitStream>
-bool HuffmanStream<BitStream>::sign(int &val)
-{
-	quint32 bit;
-	val = 0;
-
-	if (!_bs.read(1, bit))
-		return false;
-	if (bit) {
-		if (!_bs.read(1, bit))
-			return false;
-		val = bit ? -1 : 1;
-	}
-
-	return true;
-}
-
 template <class BitStream>
 bool HuffmanStream<BitStream>::read(int bits, quint32 &val)
 {
@@ -102,18 +75,58 @@ bool HuffmanStream<BitStream>::readSymbol(quint32 &symbol)
 }
 
 template <class BitStream>
-bool HuffmanStream<BitStream>::readDelta(int sign, qint32 &delta)
+class HuffmanDeltaStream : public HuffmanStream<BitStream>
+{
+public:
+	HuffmanDeltaStream(BitStream &bitstream, const HuffmanTable &table)
+	  : HuffmanStream<BitStream>(bitstream, table), _lonSign(0), _latSign(0) {}
+
+	bool readNext(qint32 &lonDelta, qint32 &latDelta)
+	{
+		if (!(readDelta(_lonSign, lonDelta) && readDelta(_latSign, latDelta)))
+			return false;
+
+		return (lonDelta || latDelta);
+	}
+
+protected:
+	bool sign(int &val);
+	bool readDelta(int sign, qint32 &delta);
+
+	int _lonSign, _latSign;
+};
+
+template <class BitStream>
+bool HuffmanDeltaStream<BitStream>::sign(int &val)
+{
+	quint32 bit;
+	val = 0;
+
+	if (!this->read(1, bit))
+		return false;
+	if (bit) {
+		if (!this->read(1, bit))
+			return false;
+		val = bit ? -1 : 1;
+	}
+
+	return true;
+}
+
+template <class BitStream>
+bool HuffmanDeltaStream<BitStream>::readDelta(int sign, qint32 &delta)
 {
 	quint32 symbol;
-	if (!readSymbol(symbol))
+	if (!this->readSymbol(symbol))
 		return false;
 
 	if (symbol && !sign) {
-		if (!_symbolDataSize)
+		if (!this->_symbolDataSize)
 			return false;
 		else {
-			sign = ((1U << (_symbolDataSize - 1)) & _symbolData) ? -1 : 1;
-			_symbolDataSize--;
+			sign = ((1U << (this->_symbolDataSize - 1)) & this->_symbolData)
+			  ? -1 : 1;
+			this->_symbolDataSize--;
 		}
 	}
 	delta = sign * symbol;
@@ -121,23 +134,23 @@ bool HuffmanStream<BitStream>::readDelta(int sign, qint32 &delta)
 	return true;
 }
 
-class HuffmanStreamF : public HuffmanStream<BitStream4F> {
+class HuffmanDeltaStreamF : public HuffmanDeltaStream<BitStream4F> {
 public:
-	HuffmanStreamF(BitStream4F &bitstream, const HuffmanTable &table)
-	  : HuffmanStream(bitstream, table) {}
+	HuffmanDeltaStreamF(BitStream4F &bitstream, const HuffmanTable &table)
+	  : HuffmanDeltaStream(bitstream, table) {}
 
 	bool init(bool line);
 	bool readOffset(qint32 &lonDelta, qint32 &latDelta)
 	  {return (readDelta(1, lonDelta) && readDelta(1, latDelta));}
 };
 
-class HuffmanStreamR : public HuffmanStream<BitStream4R> {
+class HuffmanDeltaStreamR : public HuffmanDeltaStream<BitStream4R> {
 public:
-	HuffmanStreamR(BitStream4R &bitstream, const HuffmanTable &table)
-	  : HuffmanStream(bitstream, table) {}
+	HuffmanDeltaStreamR(BitStream4R &bitstream, const HuffmanTable &table)
+	  : HuffmanDeltaStream(bitstream, table) {}
 
 	bool init();
-	bool init(int lonSign, int latSign, quint32 data, quint32 dataSize);
+	bool init(quint32 data, quint32 dataSize);
 };
 
 }
diff --git a/src/map/IMG/netfile.cpp b/src/map/IMG/netfile.cpp
index 62c3377e..8d3af3d0 100644
--- a/src/map/IMG/netfile.cpp
+++ b/src/map/IMG/netfile.cpp
@@ -116,7 +116,7 @@ static bool readLine(BitStream4R &bs, const SubDiv *subdiv,
 	poly.boundingRect = RectC(c, c);
 	poly.points.append(QPointF(c.lon(), c.lat()));
 
-	HuffmanStreamR stream(bs, *table);
+	HuffmanDeltaStreamR stream(bs, *table);
 	if (!stream.init())
 		return false;
 	qint32 lonDelta, latDelta;
@@ -164,18 +164,6 @@ static bool skipNodes(const NODFile *nod, SubFile::Handle &nodHdl,
 	return true;
 }
 
-static int sign(quint32 flags, quint32 &bits)
-{
-	if (!((flags >> bits) & 1)) {
-		bits--;
-		return 0;
-	} else {
-		quint32 sb = bits - 1;
-		bits -= 2;
-		return ((flags >> sb) & 1) ? -1 : 1;
-	}
-}
-
 static bool readShape(const NODFile *nod, SubFile::Handle &nodHdl,
   NODFile::AdjacencyInfo &adj, BitStream4R &bs, const HuffmanTable *table,
   const SubDiv *subdiv, quint32 shift, MapData::Poly &poly,
@@ -197,12 +185,8 @@ static bool readShape(const NODFile *nod, SubFile::Handle &nodHdl,
 	bool startWithStream = flags & (1 << (v2b + 6));
 	bool useEosBit = flags & (1 << (v2b + 5));
 
-	quint32 extraBits = v2b + 4;
-	int lonSign = sign(flags, extraBits);
-	int latSign = sign(flags, extraBits);
-
-	HuffmanStreamR stream(bs, *table);
-	if (!stream.init(lonSign, latSign, flags, extraBits + 1))
+	HuffmanDeltaStreamR stream(bs, *table);
+	if (!stream.init(flags, v2b + 5))
 		return false;
 
 
diff --git a/src/map/IMG/rgnfile.cpp b/src/map/IMG/rgnfile.cpp
index 0e48cadd..d345032c 100644
--- a/src/map/IMG/rgnfile.cpp
+++ b/src/map/IMG/rgnfile.cpp
@@ -287,7 +287,7 @@ bool RGNFile::extPolyObjects(Handle &hdl, const SubDiv *subdiv, quint32 shift,
 
 			qint32 lonDelta, latDelta;
 			BitStream4F bs(*this, hdl, len);
-			HuffmanStreamF stream(bs, *_huffmanTable);
+			HuffmanDeltaStreamF stream(bs, *_huffmanTable);
 			if (!stream.init(segmentType == Line))
 				return false;