diff --git a/source/output.cpp b/source/output.cpp
index 7465b77..5aa01d0 100644
--- a/source/output.cpp
+++ b/source/output.cpp
@@ -47,7 +47,7 @@ static void drawFrame(gfxScreen_t screen, char b, char g, char r)
     int screenWidth = (screen == GFX_TOP) ? 400 : 320;
     std::string& textBuffer = (screen == GFX_TOP) ? bufferTop : bufferBottom;
 
-    u8* bufAdr = gfxGetFramebuffer(screen, GFX_LEFT, NULL, NULL);
+    u8* bufAdr = gfxGetFramebuffer(screen, GFX_LEFT, nullptr, nullptr);
     for (int i = 0; i < screenWidth * screenHeight * 3; i += 3) {
         bufAdr[i]   = b;
         bufAdr[i+1] = g;
@@ -59,7 +59,7 @@ static void drawFrame(gfxScreen_t screen, char b, char g, char r)
         deleteFirstLine(&textBuffer);
         lines--;
     }
-    gfxDrawText(screen, GFX_LEFT, NULL, textBuffer.c_str(), screenHeight - fontDefault.height * 3, 10);
+    gfxDrawText(screen, GFX_LEFT, nullptr, textBuffer, screenHeight - fontDefault.height * 3, 10);
 }
 
 void drawFrames()
diff --git a/source/text.cpp b/source/text.cpp
index 2c5d8fa..f3e13c6 100644
--- a/source/text.cpp
+++ b/source/text.cpp
@@ -35,10 +35,9 @@ int drawCharacter(u8* fb, font_s* font, char c, s16 x, s16 y, u16 w, u16 h)
     const u8 g = font->color[1];
     const u8 b = font->color[2];
 
-    int i, j;
-    for (i = 0; i < cd->w; i++) {
+    for (int i = 0; i < cd->w; i++) {
         charData += cyo;
-        for(j = 0; j < ch; j++) {
+        for (int j = 0; j < ch; j++) {
             u8 v = *(charData++);
             if (v) {
                 fb[0] = (fb[0] * (0xFF - v) + (b * v)) >> 8;
@@ -53,28 +52,25 @@ int drawCharacter(u8* fb, font_s* font, char c, s16 x, s16 y, u16 w, u16 h)
     return cd->xa;
 }
 
-void drawString(u8* fb, font_s* f, const char* str, s16 x, s16 y, u16 w, u16 h)
+void drawString(u8* fb, font_s* f, const std::string& str, s16 x, s16 y, u16 w, u16 h)
 {
-    if (!f || !fb || !str)
+    if (!f || !fb)
         return;
 
-    int k, dx = 0, dy = 0;
-    int length = strlen(str);
-    for (k = 0; k < length; k++)
+    int dx = 0, dy = 0;
+    for (const char& c : str)
     {
-        dx += drawCharacter(fb, f, str[k], x + dx, y + dy, w, h);
-        if(str[k]=='\n') {
+        dx += drawCharacter(fb, f, c, x + dx, y + dy, w, h);
+        if (c == '\n') {
             dx = 0;
             dy -= f->height;
         }
     }
 }
 
-void gfxDrawText(gfxScreen_t screen, gfx3dSide_t side, font_s* font, const char* str, s16 x, s16 y)
+void gfxDrawText(gfxScreen_t screen, gfx3dSide_t side, font_s* font, const std::string& str, s16 x, s16 y)
 {
-    if(!str)
-        return;
-    if(!font)
+    if (!font)
         font = &fontDefault;
 
     u16 fbWidth, fbHeight;
diff --git a/source/text.h b/source/text.h
index 035e475..719d5c3 100644
--- a/source/text.h
+++ b/source/text.h
@@ -1,9 +1,9 @@
 #pragma once
 
-#include <stdio.h>
+#include <string>
 
 #include "font.h"
 
 int drawCharacter(u8* fb, font_s* f, char c, s16 x, s16 y, u16 w, u16 h);
-void drawString(u8* fb, font_s* f, const char* str, s16 x, s16 y, u16 w, u16 h);
-void gfxDrawText(gfxScreen_t screen, gfx3dSide_t side, font_s* f, const char* str, s16 x, s16 y);
+void drawString(u8* fb, font_s* f, const std::string& str, s16 x, s16 y, u16 w, u16 h);
+void gfxDrawText(gfxScreen_t screen, gfx3dSide_t side, font_s* f, const std::string& str, s16 x, s16 y);