diff --git a/src/gui/LauncherDialog.cxx b/src/gui/LauncherDialog.cxx
index 7a58e215d..c33832ce9 100644
--- a/src/gui/LauncherDialog.cxx
+++ b/src/gui/LauncherDialog.cxx
@@ -384,7 +384,7 @@ void LauncherDialog::setRomInfoFont(const Common::Size& area)
   };
 
   // Try to pick a font that works best, based on the available area
-  for(int i = 0; i < sizeof(FONTS) / sizeof(FontDesc); ++i)
+  for(size_t i = 0; i < sizeof(FONTS) / sizeof(FontDesc); ++i)
   {
     // only use fonts <= launcher fonts
     if(instance().frameBuffer().launcherFont().getFontHeight() >= FONTS[i].height)
diff --git a/src/gui/Stella14x28tFont.hxx b/src/gui/Stella14x28tFont.hxx
index 28151f725..2ce818d7c 100644
--- a/src/gui/Stella14x28tFont.hxx
+++ b/src/gui/Stella14x28tFont.hxx
@@ -6325,9 +6325,9 @@ static const FontDesc stella14x28tDesc = {
   29,
   98,
   stella14x28t_font_bits,
-  0,  /* no encode table*/
-  0,  /* fixed width*/
-  0,  /* fixed bbox*/
+  nullptr,  /* no encode table*/
+  nullptr,  /* fixed width*/
+  nullptr,  /* fixed bbox*/
   32,
   sizeof(stella14x28t_font_bits)/sizeof(uInt16)
 };
diff --git a/src/gui/Stella16x32tFont.hxx b/src/gui/Stella16x32tFont.hxx
index 0f74d3b4e..15c1e7b4c 100644
--- a/src/gui/Stella16x32tFont.hxx
+++ b/src/gui/Stella16x32tFont.hxx
@@ -7109,9 +7109,9 @@ static const FontDesc stella16x32tDesc = {
   29,
   98,
   stella16x32t_font_bits,
-  0,  /* no encode table*/
-  0,  /* fixed width*/
-  0,  /* fixed bbox*/
+  nullptr,  /* no encode table*/
+  nullptr,  /* fixed width*/
+  nullptr,  /* fixed bbox*/
   32,
   sizeof(stella16x32t_font_bits)/sizeof(uInt16)
 };
diff --git a/src/tools/convbdf.c b/src/tools/convbdf.c
index d6c661567..992095600 100644
--- a/src/tools/convbdf.c
+++ b/src/tools/convbdf.c
@@ -936,17 +936,17 @@ int gen_c_source(struct font* pf, char *path)
   if (pf->offset)
     sprintf(obuf, "%s_sysfont_offset,", fontname);
   else
-    sprintf(obuf, "0,  /* no encode table*/");
+    sprintf(obuf, "nullptr,  /* no encode table*/");
 
   if (pf->width)
     sprintf(buf, "%s_sysfont_width,", fontname);
   else
-    sprintf(buf, "0,  /* fixed width*/");
+    sprintf(buf, "nullptr,  /* fixed width*/");
 
   if (pf->bbx)
     sprintf(bbuf, "%s_sysfont_bbx,", fontname);
   else
-    sprintf(bbuf, "0,  /* fixed bbox*/");
+    sprintf(bbuf, "nullptr,  /* fixed bbox*/");
 
   fprintf(ofp,
       "/* Exported structure definition. */\n"