diff --git a/common/network/Socket.h b/common/network/Socket.h
index 53f957e..874a59c 100644
--- a/common/network/Socket.h
+++ b/common/network/Socket.h
@@ -82,6 +82,7 @@
   class ConnectionFilter {
   public:
     virtual bool verifyConnection(Socket* s) = 0;
+    virtual ~ConnectionFilter() {}
   };
 
   class SocketListener {
diff --git a/common/rdr/FdInStream.h b/common/rdr/FdInStream.h
index 5d9598c..b4c8765 100644
--- a/common/rdr/FdInStream.h
+++ b/common/rdr/FdInStream.h
@@ -30,6 +30,7 @@
   class FdInStreamBlockCallback {
   public:
     virtual void blockCallback() = 0;
+    virtual ~FdInStreamBlockCallback() {}
   };
 
   class FdInStream : public InStream {
diff --git a/common/rdr/FileInStream.cxx b/common/rdr/FileInStream.cxx
index 8d5c22e..3acdfd4 100644
--- a/common/rdr/FileInStream.cxx
+++ b/common/rdr/FileInStream.cxx
@@ -70,12 +70,12 @@
 
   while (end < b + itemSize) {
     size_t n = fread((U8 *)end, b + sizeof(b) - end, 1, file);
-    if (n < 1) {
-      if (n < 0 || ferror(file))
+    if (n == 0) {
+      if (ferror(file))
         throw SystemException("fread", errno);
       if (feof(file))
         throw EndOfStream();
-      if (n == 0) { return 0; }
+      return 0;
     }
     end += b + sizeof(b) - end;
   }
diff --git a/common/rfb/CMsgWriter.h b/common/rfb/CMsgWriter.h
index b1f0119..eb9b112 100644
--- a/common/rfb/CMsgWriter.h
+++ b/common/rfb/CMsgWriter.h
@@ -33,7 +33,7 @@
 
   class PixelFormat;
   class ConnParams;
-  class ScreenSet;
+  struct ScreenSet;
   struct Rect;
 
   class CMsgWriter : public InputHandler {
diff --git a/common/rfb/Configuration.h b/common/rfb/Configuration.h
index fbf161d..d319915 100644
--- a/common/rfb/Configuration.h
+++ b/common/rfb/Configuration.h
@@ -215,6 +215,7 @@
     IntParameter(const char* name_, const char* desc_, int v,
                  int minValue=INT_MIN, int maxValue=INT_MAX,
 		 ConfigurationObject co=ConfGlobal);
+    using VoidParameter::setParam;
     virtual bool setParam(const char* value);
     virtual bool setParam(int v);
     virtual char* getDefaultStr() const;
@@ -251,6 +252,7 @@
   public:
     BinaryParameter(const char* name_, const char* desc_, const void* v, int l,
 		    ConfigurationObject co=ConfGlobal);
+    using VoidParameter::setParam;
     virtual ~BinaryParameter();
     virtual bool setParam(const char* value);
     virtual void setParam(const void* v, int l);
diff --git a/common/rfb/DecodeManager.h b/common/rfb/DecodeManager.h
index fbb7f77..2098063 100644
--- a/common/rfb/DecodeManager.h
+++ b/common/rfb/DecodeManager.h
@@ -32,7 +32,7 @@
 }
 
 namespace rdr {
-  class Exception;
+  struct Exception;
   class MemOutStream;
 }
 
@@ -40,7 +40,7 @@
   class CConnection;
   class Decoder;
   class ModifiablePixelBuffer;
-  class Rect;
+  struct Rect;
 
   class DecodeManager {
   public:
diff --git a/common/rfb/Decoder.h b/common/rfb/Decoder.h
index 3840b3f..86ee4ef 100644
--- a/common/rfb/Decoder.h
+++ b/common/rfb/Decoder.h
@@ -27,9 +27,10 @@
 namespace rfb {
   class ConnParams;
   class ModifiablePixelBuffer;
-  class Rect;
   class Region;
 
+  struct Rect;
+
   enum DecoderFlags {
     // A constant for decoders that don't need anything special
     DecoderPlain = 0,
diff --git a/common/rfb/EncodeManager.h b/common/rfb/EncodeManager.h
index 79db950..4319b42 100644
--- a/common/rfb/EncodeManager.h
+++ b/common/rfb/EncodeManager.h
@@ -32,7 +32,7 @@
   class PixelBuffer;
   class RenderedCursor;
   class Region;
-  class Rect;
+  struct Rect;
 
   struct RectInfo;
 
diff --git a/common/rfb/InputHandler.h b/common/rfb/InputHandler.h
index 0344bc3..6c07284 100644
--- a/common/rfb/InputHandler.h
+++ b/common/rfb/InputHandler.h
@@ -25,15 +25,20 @@
 
 #include <rdr/types.h>
 #include <rfb/Rect.h>
+#include <rfb/util.h>
 
 namespace rfb {
 
   class InputHandler {
   public:
     virtual ~InputHandler() {}
-    virtual void keyEvent(rdr::U32 keysym, rdr::U32 keycode, bool down) {}
-    virtual void pointerEvent(const Point& pos, int buttonMask) {}
-    virtual void clientCutText(const char* str, int len) {}
+    virtual void keyEvent(rdr::U32 __unused_attr keysym,
+                          rdr::U32 __unused_attr keycode,
+                          bool __unused_attr down) { }
+    virtual void pointerEvent(const Point& __unused_attr pos,
+                              int __unused_attr buttonMask) { }
+    virtual void clientCutText(const char* __unused_attr str,
+                               int __unused_attr len) { }
   };
 
 }
diff --git a/common/rfb/LogWriter.h b/common/rfb/LogWriter.h
index 69b530c..104a875 100644
--- a/common/rfb/LogWriter.h
+++ b/common/rfb/LogWriter.h
@@ -36,9 +36,9 @@
 // is assigned a particular log level.
 
 #define DEF_LOGFUNCTION(name, level) \
-  inline void v##name(const char* fmt, va_list ap) { \
-    if (m_log && (level <= m_level))       \
-      m_log->write(level, m_name, fmt, ap);\
+  inline void v##name(const char* fmt, va_list ap) __printf_attr(2, 0) { \
+    if (m_log && (level <= m_level))        \
+      m_log->write(level, m_name, fmt, ap); \
   } \
   inline void name(const char* fmt, ...) __printf_attr(2, 3) { \
     if (m_log && (level <= m_level)) {     \
diff --git a/common/rfb/Logger.h b/common/rfb/Logger.h
index e53764b..b75594c 100644
--- a/common/rfb/Logger.h
+++ b/common/rfb/Logger.h
@@ -28,6 +28,12 @@
 // and is attached to a particular Logger instance and
 // is assigned a particular log level.
 
+#ifdef __GNUC__
+#  define __printf_attr(a, b) __attribute__((__format__ (__printf__, a, b)))
+#else
+#  define __printf_attr(a, b)
+#endif // __GNUC__
+
 namespace rfb {
 
   class Logger {
@@ -45,7 +51,7 @@
     // -=- Write data to a log
 
     virtual void write(int level, const char *logname, const char *text) = 0;
-    void write(int level, const char *logname, const char* format, va_list ap);
+    void write(int level, const char *logname, const char* format, va_list ap) __printf_attr(4, 0);
 
     // -=- Register a logger
 
diff --git a/common/rfb/PixelBuffer.h b/common/rfb/PixelBuffer.h
index 75caa63..d89793f 100644
--- a/common/rfb/PixelBuffer.h
+++ b/common/rfb/PixelBuffer.h
@@ -28,6 +28,7 @@
 #include <rfb/PixelFormat.h>
 #include <rfb/Rect.h>
 #include <rfb/Pixel.h>
+#include <rfb/util.h>
 
 namespace rfb {
 
@@ -85,7 +86,7 @@
     // Ensure that the specified rectangle of buffer is up to date.
     //   Overridden by derived classes implementing framebuffer access
     //   to copy the required display data into place.
-    virtual void grabRegion(const Region& region) {}
+    virtual void grabRegion(const Region& __unused_attr region) {}
 
   protected:
     PixelBuffer();
diff --git a/common/rfb/SDesktop.h b/common/rfb/SDesktop.h
index 833762e..322fe32 100644
--- a/common/rfb/SDesktop.h
+++ b/common/rfb/SDesktop.h
@@ -42,6 +42,7 @@
 #include <rfb/InputHandler.h>
 #include <rfb/Exception.h>
 #include <rfb/screenTypes.h>
+#include <rfb/util.h>
 
 namespace rfb {
 
@@ -55,7 +56,7 @@
     // set via the VNCServer's setPixelBuffer() method by the time this call
     // returns.
 
-    virtual void start(VNCServer* vs) {}
+    virtual void start(VNCServer* __unused_attr vs) {}
 
     // stop() is called by the server when there are no longer any
     // authenticated clients, and therefore the desktop can cease any
@@ -71,8 +72,9 @@
 
     // setScreenLayout() requests to reconfigure the framebuffer and/or
     // the layout of screens.
-    virtual unsigned int setScreenLayout(int fb_width, int fb_height,
-                                         const ScreenSet& layout) {
+    virtual unsigned int setScreenLayout(int __unused_attr fb_width,
+                                         int __unused_attr fb_height,
+                                         const ScreenSet& __unused_attr layout) {
       return resultProhibited;
     }
 
diff --git a/common/rfb/SMsgWriter.h b/common/rfb/SMsgWriter.h
index 7660b11..e985941 100644
--- a/common/rfb/SMsgWriter.h
+++ b/common/rfb/SMsgWriter.h
@@ -32,7 +32,7 @@
 namespace rfb {
 
   class ConnParams;
-  class ScreenSet;
+  struct ScreenSet;
 
   class SMsgWriter {
   public:
diff --git a/common/rfb/SSecurityPlain.h b/common/rfb/SSecurityPlain.h
index 2c08c24..4bf42b7 100644
--- a/common/rfb/SSecurityPlain.h
+++ b/common/rfb/SSecurityPlain.h
@@ -38,6 +38,8 @@
       { return validUser(username) ? validateInternal(sc, username, password) : false; }
     static StringParameter plainUsers;
 
+    virtual ~PasswordValidator() { }
+
   protected:
     virtual bool validateInternal(SConnection* sc, const char *username, const char *password)=0;
     static bool validUser(const char* username);
@@ -50,6 +52,8 @@
     virtual int getType() const { return secTypePlain; };
     virtual const char* getUserName() const { return username.buf; }
 
+    virtual ~SSecurityPlain() { }
+
   private:
     PasswordValidator* valid;
     unsigned int ulen, plen, state;
diff --git a/common/rfb/SSecurityVncAuth.h b/common/rfb/SSecurityVncAuth.h
index e9f379b..a1d1747 100644
--- a/common/rfb/SSecurityVncAuth.h
+++ b/common/rfb/SSecurityVncAuth.h
@@ -37,6 +37,8 @@
     // getVncAuthPasswd() fills buffer of given password and readOnlyPassword.
     // If there was no read only password in the file, readOnlyPassword buffer is null.
     virtual void getVncAuthPasswd(PlainPasswd *password, PlainPasswd *readOnlyPassword)=0;
+
+    virtual ~VncAuthPasswdGetter() { }
   };
 
   class VncAuthPasswdParameter : public VncAuthPasswdGetter, BinaryParameter {
diff --git a/common/rfb/Timer.h b/common/rfb/Timer.h
index e295b82..78687d1 100644
--- a/common/rfb/Timer.h
+++ b/common/rfb/Timer.h
@@ -49,6 +49,8 @@
       //   appropriate interval.
       //   If the handler returns false then the Timer is cancelled.
       virtual bool handleTimeout(Timer* t) = 0;
+
+      virtual ~Callback() {}
     };
 
     // checkTimeouts()
diff --git a/common/rfb/UserPasswdGetter.h b/common/rfb/UserPasswdGetter.h
index 13493e4..27775cc 100644
--- a/common/rfb/UserPasswdGetter.h
+++ b/common/rfb/UserPasswdGetter.h
@@ -25,6 +25,8 @@
     // case no user name will be retrieved.  The caller MUST delete [] the
     // result(s).
     virtual void getUserPasswd(bool secure, char** user, char** password)=0;
+
+    virtual ~UserPasswdGetter() {}
   };
 }
 #endif
diff --git a/common/rfb/util.cxx b/common/rfb/util.cxx
index 22e00ff..cfec2ef 100644
--- a/common/rfb/util.cxx
+++ b/common/rfb/util.cxx
@@ -44,7 +44,7 @@
 
   void CharArray::format(const char *fmt, ...) {
     va_list ap;
-    size_t len;
+    int len;
 
     va_start(ap, fmt);
     len = vsnprintf(NULL, 0, fmt, ap);
diff --git a/common/rfb/util.h b/common/rfb/util.h
index e9114c3..0de64c4 100644
--- a/common/rfb/util.h
+++ b/common/rfb/util.h
@@ -38,6 +38,10 @@
 #  define __printf_attr(a, b)
 #endif // __GNUC__
 
+#ifndef __unused_attr
+#  define __unused_attr __attribute((__unused__))
+#endif
+
 namespace rfb {
 
   // -=- Class to handle cleanup of arrays of characters