diff --git a/src/util.cpp b/src/util.cpp
index 78c353dfe..30c530cb4 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -97,15 +97,15 @@ namespace boost {
 
 } // namespace boost
 
-using namespace std;
+
 
 const char * const BITCOIN_CONF_FILENAME = "bitcoin.conf";
 const char * const BITCOIN_PID_FILENAME = "bitcoind.pid";
 
 CCriticalSection cs_args;
-map<string, string> mapArgs;
-static map<string, vector<string> > _mapMultiArgs;
-const map<string, vector<string> >& mapMultiArgs = _mapMultiArgs;
+std::map<std::string, std::string> mapArgs;
+static std::map<std::string, std::vector<std::string> > _mapMultiArgs;
+const std::map<std::string, std::vector<std::string> >& mapMultiArgs = _mapMultiArgs;
 bool fDebug = false;
 bool fPrintToConsole = false;
 bool fPrintToDebugLog = true;
@@ -191,7 +191,7 @@ static boost::once_flag debugPrintInitFlag = BOOST_ONCE_INIT;
  */
 static FILE* fileout = NULL;
 static boost::mutex* mutexDebugLog = NULL;
-static list<string> *vMsgsBeforeOpenLog;
+static std::list<std::string>* vMsgsBeforeOpenLog;
 
 static int FileWriteStr(const std::string &str, FILE *fp)
 {
@@ -202,7 +202,7 @@ static void DebugPrintInit()
 {
     assert(mutexDebugLog == NULL);
     mutexDebugLog = new boost::mutex();
-    vMsgsBeforeOpenLog = new list<string>;
+    vMsgsBeforeOpenLog = new std::list<std::string>;
 }
 
 void OpenDebugLog()
@@ -238,22 +238,22 @@ bool LogAcceptCategory(const char* category)
         // This helps prevent issues debugging global destructors,
         // where mapMultiArgs might be deleted before another
         // global destructor calls LogPrint()
-        static boost::thread_specific_ptr<set<string> > ptrCategory;
+        static boost::thread_specific_ptr<std::set<std::string> > ptrCategory;
         if (ptrCategory.get() == NULL)
         {
             if (mapMultiArgs.count("-debug")) {
-                const vector<string>& categories = mapMultiArgs.at("-debug");
-                ptrCategory.reset(new set<string>(categories.begin(), categories.end()));
+                const std::vector<std::string>& categories = mapMultiArgs.at("-debug");
+                ptrCategory.reset(new std::set<std::string>(categories.begin(), categories.end()));
                 // thread_specific_ptr automatically deletes the set when the thread ends.
             } else
-                ptrCategory.reset(new set<string>());
+                ptrCategory.reset(new std::set<std::string>());
         }
-        const set<string>& setCategories = *ptrCategory.get();
+        const std::set<std::string>& setCategories = *ptrCategory.get();
 
         // if not debugging everything and not debugging specific category, LogPrint does nothing.
-        if (setCategories.count(string("")) == 0 &&
-            setCategories.count(string("1")) == 0 &&
-            setCategories.count(string(category)) == 0)
+        if (setCategories.count(std::string("")) == 0 &&
+            setCategories.count(std::string("1")) == 0 &&
+            setCategories.count(std::string(category)) == 0)
             return false;
     }
     return true;
@@ -266,7 +266,7 @@ bool LogAcceptCategory(const char* category)
  */
 static std::string LogTimestampStr(const std::string &str, std::atomic_bool *fStartedNewLine)
 {
-    string strStamped;
+    std::string strStamped;
 
     if (!fLogTimestamps)
         return str;
@@ -293,7 +293,7 @@ int LogPrintStr(const std::string &str)
     int ret = 0; // Returns total number of characters written
     static std::atomic_bool fStartedNewLine(true);
 
-    string strTimestamped = LogTimestampStr(str, &fStartedNewLine);
+    std::string strTimestamped = LogTimestampStr(str, &fStartedNewLine);
 
     if (fPrintToConsole)
     {
@@ -561,14 +561,14 @@ void ReadConfigFile(const std::string& confPath)
 
     {
         LOCK(cs_args);
-        set<string> setOptions;
+        std::set<std::string> setOptions;
         setOptions.insert("*");
 
         for (boost::program_options::detail::config_file_iterator it(streamConfig, setOptions), end; it != end; ++it)
         {
             // Don't overwrite existing settings so command line settings override bitcoin.conf
-            string strKey = string("-") + it->string_key;
-            string strValue = it->value[0];
+            std::string strKey = std::string("-") + it->string_key;
+            std::string strValue = it->value[0];
             InterpretNegativeSetting(strKey, strValue);
             if (mapArgs.count(strKey) == 0)
                 mapArgs[strKey] = strValue;
diff --git a/src/utilmoneystr.cpp b/src/utilmoneystr.cpp
index bebe56130..6e6e33184 100644
--- a/src/utilmoneystr.cpp
+++ b/src/utilmoneystr.cpp
@@ -9,8 +9,6 @@
 #include "tinyformat.h"
 #include "utilstrencodings.h"
 
-using namespace std;
-
 std::string FormatMoney(const CAmount& n)
 {
     // Note: not using straight sprintf here because we do NOT want
@@ -18,7 +16,7 @@ std::string FormatMoney(const CAmount& n)
     int64_t n_abs = (n > 0 ? n : -n);
     int64_t quotient = n_abs/COIN;
     int64_t remainder = n_abs%COIN;
-    string str = strprintf("%d.%08d", quotient, remainder);
+    std::string str = strprintf("%d.%08d", quotient, remainder);
 
     // Right-trim excess zeros before the decimal point:
     int nTrim = 0;
@@ -33,14 +31,14 @@ std::string FormatMoney(const CAmount& n)
 }
 
 
-bool ParseMoney(const string& str, CAmount& nRet)
+bool ParseMoney(const std::string& str, CAmount& nRet)
 {
     return ParseMoney(str.c_str(), nRet);
 }
 
 bool ParseMoney(const char* pszIn, CAmount& nRet)
 {
-    string strWhole;
+    std::string strWhole;
     int64_t nUnits = 0;
     const char* p = pszIn;
     while (isspace(*p))
diff --git a/src/utilstrencodings.cpp b/src/utilstrencodings.cpp
index 29ae57940..74bf66fbf 100644
--- a/src/utilstrencodings.cpp
+++ b/src/utilstrencodings.cpp
@@ -12,20 +12,18 @@
 #include <errno.h>
 #include <limits>
 
-using namespace std;
+static const std::string CHARS_ALPHA_NUM = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 
-static const string CHARS_ALPHA_NUM = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
-static const string SAFE_CHARS[] =
+static const std::string SAFE_CHARS[] =
 {
     CHARS_ALPHA_NUM + " .,;-_/:?@()", // SAFE_CHARS_DEFAULT
     CHARS_ALPHA_NUM + " .,;-_?@", // SAFE_CHARS_UA_COMMENT
     CHARS_ALPHA_NUM + ".-_", // SAFE_CHARS_FILENAME
 };
 
-string SanitizeString(const string& str, int rule)
+std::string SanitizeString(const std::string& str, int rule)
 {
-    string strResult;
+    std::string strResult;
     for (std::string::size_type i = 0; i < str.size(); i++)
     {
         if (SAFE_CHARS[rule].find(str[i]) != std::string::npos)
@@ -57,7 +55,7 @@ signed char HexDigit(char c)
     return p_util_hexdigit[(unsigned char)c];
 }
 
-bool IsHex(const string& str)
+bool IsHex(const std::string& str)
 {
     for(std::string::const_iterator it(str.begin()); it != str.end(); ++it)
     {
@@ -67,10 +65,10 @@ bool IsHex(const string& str)
     return (str.size() > 0) && (str.size()%2 == 0);
 }
 
-vector<unsigned char> ParseHex(const char* psz)
+std::vector<unsigned char> ParseHex(const char* psz)
 {
     // convert hex dump to vector
-    vector<unsigned char> vch;
+    std::vector<unsigned char> vch;
     while (true)
     {
         while (isspace(*psz))
@@ -88,16 +86,16 @@ vector<unsigned char> ParseHex(const char* psz)
     return vch;
 }
 
-vector<unsigned char> ParseHex(const string& str)
+std::vector<unsigned char> ParseHex(const std::string& str)
 {
     return ParseHex(str.c_str());
 }
 
-string EncodeBase64(const unsigned char* pch, size_t len)
+std::string EncodeBase64(const unsigned char* pch, size_t len)
 {
     static const char *pbase64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
-    string strRet="";
+    std::string strRet = "";
     strRet.reserve((len+2)/3*4);
 
     int mode=0, left=0;
@@ -139,12 +137,12 @@ string EncodeBase64(const unsigned char* pch, size_t len)
     return strRet;
 }
 
-string EncodeBase64(const string& str)
+std::string EncodeBase64(const std::string& str)
 {
     return EncodeBase64((const unsigned char*)str.c_str(), str.size());
 }
 
-vector<unsigned char> DecodeBase64(const char* p, bool* pfInvalid)
+std::vector<unsigned char> DecodeBase64(const char* p, bool* pfInvalid)
 {
     static const int decode64_table[256] =
     {
@@ -166,7 +164,7 @@ vector<unsigned char> DecodeBase64(const char* p, bool* pfInvalid)
     if (pfInvalid)
         *pfInvalid = false;
 
-    vector<unsigned char> vchRet;
+    std::vector<unsigned char> vchRet;
     vchRet.reserve(strlen(p)*3/4);
 
     int mode = 0;
@@ -227,17 +225,17 @@ vector<unsigned char> DecodeBase64(const char* p, bool* pfInvalid)
     return vchRet;
 }
 
-string DecodeBase64(const string& str)
+std::string DecodeBase64(const std::string& str)
 {
-    vector<unsigned char> vchRet = DecodeBase64(str.c_str());
-    return (vchRet.size() == 0) ? string() : string((const char*)&vchRet[0], vchRet.size());
+    std::vector<unsigned char> vchRet = DecodeBase64(str.c_str());
+    return (vchRet.size() == 0) ? std::string() : std::string((const char*)&vchRet[0], vchRet.size());
 }
 
-string EncodeBase32(const unsigned char* pch, size_t len)
+std::string EncodeBase32(const unsigned char* pch, size_t len)
 {
     static const char *pbase32 = "abcdefghijklmnopqrstuvwxyz234567";
 
-    string strRet="";
+    std::string strRet="";
     strRet.reserve((len+4)/5*8);
 
     int mode=0, left=0;
@@ -292,12 +290,12 @@ string EncodeBase32(const unsigned char* pch, size_t len)
     return strRet;
 }
 
-string EncodeBase32(const string& str)
+std::string EncodeBase32(const std::string& str)
 {
     return EncodeBase32((const unsigned char*)str.c_str(), str.size());
 }
 
-vector<unsigned char> DecodeBase32(const char* p, bool* pfInvalid)
+std::vector<unsigned char> DecodeBase32(const char* p, bool* pfInvalid)
 {
     static const int decode32_table[256] =
     {
@@ -319,7 +317,7 @@ vector<unsigned char> DecodeBase32(const char* p, bool* pfInvalid)
     if (pfInvalid)
         *pfInvalid = false;
 
-    vector<unsigned char> vchRet;
+    std::vector<unsigned char> vchRet;
     vchRet.reserve((strlen(p))*5/8);
 
     int mode = 0;
@@ -414,10 +412,10 @@ vector<unsigned char> DecodeBase32(const char* p, bool* pfInvalid)
     return vchRet;
 }
 
-string DecodeBase32(const string& str)
+std::string DecodeBase32(const std::string& str)
 {
-    vector<unsigned char> vchRet = DecodeBase32(str.c_str());
-    return (vchRet.size() == 0) ? string() : string((const char*)&vchRet[0], vchRet.size());
+    std::vector<unsigned char> vchRet = DecodeBase32(str.c_str());
+    return (vchRet.size() == 0) ? std::string() : std::string((const char*)&vchRet[0], vchRet.size());
 }
 
 static bool ParsePrechecks(const std::string& str)
diff --git a/src/utiltime.cpp b/src/utiltime.cpp
index c7b3e4f16..a9936a645 100644
--- a/src/utiltime.cpp
+++ b/src/utiltime.cpp
@@ -12,8 +12,6 @@
 #include <boost/date_time/posix_time/posix_time.hpp>
 #include <boost/thread.hpp>
 
-using namespace std;
-
 static int64_t nMockTime = 0; //!< For unit testing
 
 int64_t GetTime()