diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index 637016f..14cf618 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -105,8 +105,7 @@ static inline char *duplicateStringValue(const char *value,
 /** Free the string duplicated by duplicateStringValue().
  */
 static inline void releaseStringValue(char *value) {
-  if (value)
-    free(value);
+  free(value);
 }
 
 } // namespace Json
diff --git a/src/lib_json/json_writer.cpp b/src/lib_json/json_writer.cpp
index 76a3fb5..e52fe4a 100644
--- a/src/lib_json/json_writer.cpp
+++ b/src/lib_json/json_writer.cpp
@@ -67,6 +67,7 @@ std::string valueToString(double value) {
   // Allocate a buffer that is more than large enough to store the 16 digits of
   // precision requested below.
   char buffer[32];
+  int len = -1;
 
 // Print into the buffer. We need not request the alternative representation
 // that always has a decimal point because JSON doesn't distingish the
@@ -75,36 +76,35 @@ std::string valueToString(double value) {
                                                       // visual studio 2005 to
                                                       // avoid warning.
   #if defined(WINCE)
-  _snprintf(buffer, sizeof(buffer), "%.16g", value);
+  len = _snprintf(buffer, sizeof(buffer), "%.16g", value);
   #else
-  sprintf_s(buffer, sizeof(buffer), "%.16g", value);
+  len = sprintf_s(buffer, sizeof(buffer), "%.16g", value);
   #endif
 #else
   if ( isfinite( value ))
   {
-     snprintf(buffer, sizeof(buffer), "%.16g", value);
+    len = snprintf(buffer, sizeof(buffer), "%.16g", value);
   }
   else
   {
      // IEEE standard states that NaN values will not compare to themselves
      if ( value != value)
      {
-        snprintf(buffer, sizeof(buffer), "null");
+        len = snprintf(buffer, sizeof(buffer), "null");
      }
      else if ( value < 0)
      {
-        snprintf(buffer, sizeof(buffer), "-1e+9999");
+        len = snprintf(buffer, sizeof(buffer), "-1e+9999");
      }
      else
      {
-        snprintf(buffer, sizeof(buffer), "1e+9999");
+        len = snprintf(buffer, sizeof(buffer), "1e+9999");
      }
-     // nothing more to do, return.
-     return buffer;
+     // For those, we do not need to call fixNumLoc, but it is fast.
   }
-
 #endif
-  fixNumericLocale(buffer, buffer + strlen(buffer));
+  assert(len>=0);
+  fixNumericLocale(buffer, buffer + len);
   return buffer;
 }