diff --git a/src/fontcache_internal.h b/src/fontcache_internal.h
--- a/src/fontcache_internal.h
+++ b/src/fontcache_internal.h
@@ -22,6 +22,9 @@ static const byte SHADOW_COLOUR = 2;
 /** Font cache for fonts that are based on a TrueType font. */
 class TrueTypeFontCache : public FontCache {
 protected:
+	static constexpr int MAX_GLYPH_DIM = 256;          ///< Maximum glyph dimensions.
+	static constexpr uint MAX_FONT_MIN_REC_SIZE = 20u; ///< Upper limit for the recommended font size in case a font file contains nonsensical values.
+
 	int req_size;  ///< Requested font size.
 	int used_size; ///< Used font size.