1 files changed, 5 insertions, 3 deletions

diff --git a/font/font.h b/font/font.h
index 13ff1c3..9d37e64 100644
--- a/font/font.h
+++ b/font/font.h
@@ -5,7 +5,7 @@
 
 static const unsigned char FontGlyphStart     = 32;  // Space.
 static const unsigned char FontGlyphEnd       = 127; // One past tilde.
-static const int           FontAtlasNumGlyphs = FontGlyphEnd - FontGlyphStart;
+static const unsigned int  FontAtlasNumGlyphs = FontGlyphEnd - FontGlyphStart;
 
 /// Font atlas header.
 typedef struct FontHeader {
@@ -32,8 +32,10 @@ FontAtlas* LoadFontAtlas(const char* path);
 static inline const unsigned char* FontGetGlyph(
     const FontAtlas* atlas, unsigned char c) {
   assert(atlas);
-  const int index = c - FontGlyphStart;
-  assert(index >= 0);
+  unsigned index = c - FontGlyphStart;
+  if (index >= FontAtlasNumGlyphs) {
+    index = '?' - FontGlyphStart;
+  }
   assert(index < FontAtlasNumGlyphs);
   return atlas->pixels +
          index * (atlas->header.glyph_width * atlas->header.glyph_height);