diff --git a/common/rfb/Password.cxx b/common/rfb/Password.cxx

index e4a508c..f555c57 100644

--- a/common/rfb/Password.cxx

+++ b/common/rfb/Password.cxx

@@ -55,7 +55,7 @@ PlainPasswd::~PlainPasswd() {

 void PlainPasswd::replaceBuf(char* b) {

   if (buf)

-    memset(buf, 0, strlen(buf));

+    memset(buf, 0, length ? length : strlen(buf));

   CharArray::replaceBuf(b);

 }

diff --git a/common/rfb/util.h b/common/rfb/util.h

index 3100f90..764692a 100644

--- a/common/rfb/util.h

+++ b/common/rfb/util.h

@@ -51,16 +51,21 @@ namespace rfb {

     CharArray() : buf(0) {}

     CharArray(char* str) : buf(str) {} // note: assumes ownership

     CharArray(size_t len) {

+      length = len;

       buf = new char[len]();

     }

     ~CharArray() {

-      delete [] buf;

+      if (buf) {

+        delete [] buf;

+        buf = nullptr;

+      }

     }

     void format(const char *fmt, ...) __printf_attr(2, 3);

     // Get the buffer pointer & clear it (i.e. caller takes ownership)

     char* takeBuf() {char* tmp = buf; buf = 0; return tmp;}

-    void replaceBuf(char* b) {delete [] buf; buf = b;}

+    void replaceBuf(char* b) {if (buf) delete [] buf; buf = b;}

     char* buf;

+    size_t length = 0;

   private:

     CharArray(const CharArray&);

     CharArray& operator=(const CharArray&);