--- src/fontcache.cpp	2015-01-03 10:13:27.648859160 +0100
+++ src/fontcache.cpp	2015-01-03 10:19:18.582854137 +0100
@@ -527,8 +527,8 @@
 	aa = (slot->bitmap.pixel_mode == FT_PIXEL_MODE_GRAY);
 
 	/* Add 1 pixel for the shadow on the medium font. Our sprite must be at least 1x1 pixel */
-	int width  = max(1, slot->bitmap.width + (this->fs == FS_NORMAL));
-	int height = max(1, slot->bitmap.rows  + (this->fs == FS_NORMAL));
+	int width  = max(1u, slot->bitmap.width + (this->fs == FS_NORMAL));
+	int height = max(1u, slot->bitmap.rows  + (this->fs == FS_NORMAL));
 
 	/* Limit glyph size to prevent overflows later on. */
 	if (width > 256 || height > 256) usererror("Font glyph is too large");