diff --git a/graphics/nxwidgets/src/cmultilinetextbox.cxx b/graphics/nxwidgets/src/cmultilinetextbox.cxx
index 85cfb8e51..2b6b5da12 100644
--- a/graphics/nxwidgets/src/cmultilinetextbox.cxx
+++ b/graphics/nxwidgets/src/cmultilinetextbox.cxx
@@ -1134,7 +1134,7 @@ bool CMultiLineTextBox::isCursorVisible(void) const
 
 nxwidget_char_t CMultiLineTextBox::getCursorChar(void) const
 {
-  if (m_cursorPos < m_text->getLength())
+  if (m_cursorPos < (int)m_text->getLength())
     {
       return m_text->getCharAt(m_cursorPos);
     }
diff --git a/graphics/nxwidgets/src/cnxstring.cxx b/graphics/nxwidgets/src/cnxstring.cxx
index 1504083ce..21491e78a 100644
--- a/graphics/nxwidgets/src/cnxstring.cxx
+++ b/graphics/nxwidgets/src/cnxstring.cxx
@@ -76,9 +76,9 @@
 #include <sys/types.h>
 #include <stdint.h>
 #include <stdbool.h>
-#include <string.h>
-#include <stdarg.h>
-#include <stdio.h>
+#include <cstring>
+#include <cstdarg>
+#include <cstdio>
 
 #include "graphics/nxwidgets/cnxstring.hxx"
 #include "graphics/nxwidgets/cstringiterator.hxx"
@@ -808,7 +808,7 @@ CNxString CNxString::format(const char *fmt, ...)
 {
   va_list args;
   va_start(args, fmt);
-  size_t len = vsnprintf(nullptr, 0, fmt, args) + 1;
+  size_t len = std::vsnprintf((FAR char *)0, 0, fmt, args) + 1;
   va_end(args);
 
   va_start(args, fmt);
diff --git a/graphics/nxwidgets/src/ctextbox.cxx b/graphics/nxwidgets/src/ctextbox.cxx
index b70351125..39bf2822a 100644
--- a/graphics/nxwidgets/src/ctextbox.cxx
+++ b/graphics/nxwidgets/src/ctextbox.cxx
@@ -306,7 +306,7 @@ void CTextBox::handleCursorControlEvent(const CWidgetEventArgs &e)
     }
   else if (control == CURSOR_RIGHT)
     {
-      if (m_cursorPos < m_text.getLength())
+      if (m_cursorPos < (int)m_text.getLength())
         {
           moveCursorToPosition(m_cursorPos + 1);
         }
@@ -572,7 +572,7 @@ const nxgl_coord_t CTextBox::getCursorXPos(void) const
 
 nxgl_coord_t CTextBox::getCursorWidth(void) const
 {
-  if (m_cursorPos < m_text.getLength())
+  if (m_cursorPos < (int)m_text.getLength())
     {
       // Cursor within the string - get the width of the character
 
@@ -639,7 +639,7 @@ void CTextBox::calculateTextPositionHorizontal(void)
   // Text is wider than box - view needs to follow the cursor
   // If cursor is at the end of the text, we can just right-align
 
-  if (m_cursorPos == m_text.getLength())
+  if (m_cursorPos == (int)m_text.getLength())
     {
       m_align.x = width - stringWidth;
       return;