diff --git a/src/bignum.h b/src/bignum.h
index 9fea3f70f..96b1b2e6a 100644
--- a/src/bignum.h
+++ b/src/bignum.h
@@ -305,7 +305,7 @@ public:
             psz++;
 
         // hex string to bignum
-        static signed char phexdigit[256] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0 };
+        static const signed char phexdigit[256] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0 };
         *this = 0;
         while (isxdigit(*psz))
         {
diff --git a/src/uint256.h b/src/uint256.h
index fc5ed2659..abd0b71e6 100644
--- a/src/uint256.h
+++ b/src/uint256.h
@@ -306,7 +306,7 @@ public:
             psz += 2;
 
         // hex string to uint
-        static unsigned char phexdigit[256] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0 };
+        static const unsigned char phexdigit[256] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0 };
         const char* pbegin = psz;
         while (phexdigit[(unsigned char)*psz] || *psz == '0')
             psz++;
diff --git a/src/util.cpp b/src/util.cpp
index d1270348e..a8bd8228e 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -274,7 +274,7 @@ inline int OutputDebugStringF(const char* pszFormat, ...)
     return ret;
 }
 
-string vstrprintf(const std::string &format, va_list ap)
+string vstrprintf(const char *format, va_list ap)
 {
     char buffer[50000];
     char* p = buffer;
@@ -284,7 +284,11 @@ string vstrprintf(const std::string &format, va_list ap)
     {
         va_list arg_ptr;
         va_copy(arg_ptr, ap);
-        ret = _vsnprintf(p, limit, format.c_str(), arg_ptr);
+#ifdef WIN32
+        ret = _vsnprintf(p, limit, format, arg_ptr);
+#else
+        ret = vsnprintf(p, limit, format, arg_ptr);
+#endif
         va_end(arg_ptr);
         if (ret >= 0 && ret < limit)
             break;
@@ -301,7 +305,7 @@ string vstrprintf(const std::string &format, va_list ap)
     return str;
 }
 
-string real_strprintf(const std::string &format, int dummy, ...)
+string real_strprintf(const char *format, int dummy, ...)
 {
     va_list arg_ptr;
     va_start(arg_ptr, dummy);
@@ -310,6 +314,15 @@ string real_strprintf(const std::string &format, int dummy, ...)
     return str;
 }
 
+string real_strprintf(const std::string &format, int dummy, ...)
+{
+    va_list arg_ptr;
+    va_start(arg_ptr, dummy);
+    string str = vstrprintf(format.c_str(), arg_ptr);
+    va_end(arg_ptr);
+    return str;
+}
+
 bool error(const char *format, ...)
 {
     va_list arg_ptr;
@@ -411,7 +424,7 @@ bool ParseMoney(const char* pszIn, int64& nRet)
 }
 
 
-static signed char phexdigit[256] =
+static const signed char phexdigit[256] =
 { -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
   -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
   -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
diff --git a/src/util.h b/src/util.h
index 2409ccb79..54b53582b 100644
--- a/src/util.h
+++ b/src/util.h
@@ -41,7 +41,6 @@ static const int64 CENT = 1000000;
 #define UBEGIN(a)           ((unsigned char*)&(a))
 #define UEND(a)             ((unsigned char*)&((&(a))[1]))
 #define ARRAYLEN(array)     (sizeof(array)/sizeof((array)[0]))
-#define printf              OutputDebugStringF
 
 #ifndef PRI64d
 #if defined(_MSC_VER) || defined(__MSVCRT__)
@@ -55,6 +54,17 @@ static const int64 CENT = 1000000;
 #endif
 #endif
 
+/* Format characters for (s)size_t and ptrdiff_t */
+#if defined(_MSC_VER) || defined(__MSVCRT__)
+  #define PRIszx    "%Ix"
+  #define PRIszu    "%Iu"
+  #define PRIszd    "%Id"
+#else
+  #define PRIszx    "%zx"
+  #define PRIszu    "%zu"
+  #define PRIszd    "%zd"
+#endif
+
 // This is needed because the foreach macro can't get over the comma in pair<t1, t2>
 #define PAIRTYPE(t1, t2)    std::pair<t1, t2>
 
@@ -80,11 +90,7 @@ T* alignup(T* p)
 #define S_IRUSR             0400
 #define S_IWUSR             0200
 #endif
-#define unlink              _unlink
 #else
-#define _vsnprintf(a,b,c,d) vsnprintf(a,b,c,d)
-#define strlwr(psz)         to_lower(psz)
-#define _strlwr(psz)        to_lower(psz)
 #define MAX_PATH            1024
 inline void Sleep(int64 n)
 {
@@ -94,6 +100,15 @@ inline void Sleep(int64 n)
 }
 #endif
 
+/* This GNU C extension enables the compiler to check the format string against the parameters provided.
+ * X is the number of the "format string" parameter, and Y is the number of the first variadic parameter.
+ * Parameters count from 1.
+ */
+#ifdef __GNUC__
+#define ATTR_WARN_PRINTF(X,Y) __attribute__((format(printf,X,Y)))
+#else
+#define ATTR_WARN_PRINTF(X,Y)
+#endif
 
 
 
@@ -121,16 +136,31 @@ extern bool fReopenDebugLog;
 
 void RandAddSeed();
 void RandAddSeedPerfmon();
-int OutputDebugStringF(const char* pszFormat, ...);
-int my_snprintf(char* buffer, size_t limit, const char* format, ...);
+int ATTR_WARN_PRINTF(1,2) OutputDebugStringF(const char* pszFormat, ...);
 
-/* It is not allowed to use va_start with a pass-by-reference argument.
-   (C++ standard, 18.7, paragraph 3). Use a dummy argument to work around this, and use a
-   macro to keep similar semantics.
+/*
+  Rationale for the real_strprintf / strprintf construction:
+    It is not allowed to use va_start with a pass-by-reference argument.
+    (C++ standard, 18.7, paragraph 3). Use a dummy argument to work around this, and use a
+    macro to keep similar semantics.
 */
+
+/** Overload strprintf for char*, so that GCC format type warnings can be given */
+std::string ATTR_WARN_PRINTF(1,3) real_strprintf(const char *format, int dummy, ...);
+/** Overload strprintf for std::string, to be able to use it with _ (translation).
+ * This will not support GCC format type warnings (-Wformat) so be careful.
+ */
 std::string real_strprintf(const std::string &format, int dummy, ...);
 #define strprintf(format, ...) real_strprintf(format, 0, __VA_ARGS__)
-std::string vstrprintf(const std::string &format, va_list ap);
+std::string vstrprintf(const char *format, va_list ap);
+
+/* Redefine printf so that it directs output to debug.log
+ *
+ * Do this *after* defining the other printf-like functions, because otherwise the
+ * __attribute__((format(printf,X,Y))) gets expanded to __attribute__((format(OutputDebugStringF,X,Y)))
+ * which confuses gcc.
+ */
+#define printf OutputDebugStringF
 
 bool error(const char *format, ...);
 void LogException(std::exception* pex, const char* pszThread);
@@ -237,9 +267,9 @@ inline int64 abs64(int64 n)
 template<typename T>
 std::string HexStr(const T itbegin, const T itend, bool fSpaces=false)
 {
-    std::vector<char> rv;
-    static char hexmap[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
-                               '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
+    std::string rv;
+    static const char hexmap[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
+                                     '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
     rv.reserve((itend-itbegin)*3);
     for(T it = itbegin; it < itend; ++it)
     {
@@ -250,7 +280,7 @@ std::string HexStr(const T itbegin, const T itend, bool fSpaces=false)
         rv.push_back(hexmap[val&15]);
     }
 
-    return std::string(rv.begin(), rv.end());
+    return rv;
 }
 
 inline std::string HexStr(const std::vector<unsigned char>& vch, bool fSpaces=false)