diff --git a/common/rfb/CopyRectDecoder.cxx b/common/rfb/CopyRectDecoder.cxx
index 52de879..32ed1b3 100644
--- a/common/rfb/CopyRectDecoder.cxx
+++ b/common/rfb/CopyRectDecoder.cxx
@@ -22,7 +22,7 @@
 
 using namespace rfb;
 
-CopyRectDecoder::CopyRectDecoder()
+CopyRectDecoder::CopyRectDecoder() : Decoder(DecoderPlain)
 {
 }
 
diff --git a/common/rfb/Decoder.cxx b/common/rfb/Decoder.cxx
index a1f4438..f9bbffc 100644
--- a/common/rfb/Decoder.cxx
+++ b/common/rfb/Decoder.cxx
@@ -28,7 +28,7 @@
 
 using namespace rfb;
 
-Decoder::Decoder()
+Decoder::Decoder(enum DecoderFlags flags) : flags(flags)
 {
 }
 
diff --git a/common/rfb/Decoder.h b/common/rfb/Decoder.h
index 7286b41..95c1466 100644
--- a/common/rfb/Decoder.h
+++ b/common/rfb/Decoder.h
@@ -28,10 +28,16 @@
   class ConnParams;
   class ModifiablePixelBuffer;
   class Rect;
+  class Region;
+
+  enum DecoderFlags {
+    // A constant for decoders that don't need anything special
+    DecoderPlain = 0,
+  };
 
   class Decoder {
   public:
-    Decoder();
+    Decoder(enum DecoderFlags flags);
     virtual ~Decoder();
 
     // These functions are the main interface to an individual decoder
@@ -58,6 +64,9 @@
   public:
     static bool supported(int encoding);
     static Decoder* createDecoder(int encoding);
+
+  public:
+    const enum DecoderFlags flags;
   };
 }
 
diff --git a/common/rfb/HextileDecoder.cxx b/common/rfb/HextileDecoder.cxx
index d1412d4..eae0040 100644
--- a/common/rfb/HextileDecoder.cxx
+++ b/common/rfb/HextileDecoder.cxx
@@ -36,7 +36,7 @@
 #include <rfb/hextileDecode.h>
 #undef BPP
 
-HextileDecoder::HextileDecoder()
+HextileDecoder::HextileDecoder() : Decoder(DecoderPlain)
 {
 }
 
diff --git a/common/rfb/RREDecoder.cxx b/common/rfb/RREDecoder.cxx
index 2dd47cc..218c9b0 100644
--- a/common/rfb/RREDecoder.cxx
+++ b/common/rfb/RREDecoder.cxx
@@ -36,7 +36,7 @@
 #include <rfb/rreDecode.h>
 #undef BPP
 
-RREDecoder::RREDecoder()
+RREDecoder::RREDecoder() : Decoder(DecoderPlain)
 {
 }
 
diff --git a/common/rfb/RawDecoder.cxx b/common/rfb/RawDecoder.cxx
index e349bda..786f154 100644
--- a/common/rfb/RawDecoder.cxx
+++ b/common/rfb/RawDecoder.cxx
@@ -25,7 +25,7 @@
 
 using namespace rfb;
 
-RawDecoder::RawDecoder()
+RawDecoder::RawDecoder() : Decoder(DecoderPlain)
 {
 }
 
diff --git a/common/rfb/TightDecoder.cxx b/common/rfb/TightDecoder.cxx
index 1bfa7a9..24236db 100644
--- a/common/rfb/TightDecoder.cxx
+++ b/common/rfb/TightDecoder.cxx
@@ -46,7 +46,7 @@
 #include <rfb/tightDecode.h>
 #undef BPP
 
-TightDecoder::TightDecoder()
+TightDecoder::TightDecoder() : Decoder(DecoderPlain)
 {
 }
 
diff --git a/common/rfb/ZRLEDecoder.cxx b/common/rfb/ZRLEDecoder.cxx
index 498152c..c9245c0 100644
--- a/common/rfb/ZRLEDecoder.cxx
+++ b/common/rfb/ZRLEDecoder.cxx
@@ -62,7 +62,7 @@
 #undef CPIXEL
 #undef BPP
 
-ZRLEDecoder::ZRLEDecoder()
+ZRLEDecoder::ZRLEDecoder() : Decoder(DecoderPlain)
 {
 }