MobileRead Forums - View Single Post - How do "Supplemental" fonts work on the Kobo

trekky0623 · 07-09-2026, 09:06 AM

I have a Kobo Clara BW running software version 4.45.23697. I have noticed many unicode characters not rendering correctly with some fonts, specifically characters like thin space (U+2009), em space (U+2003), and in one book the "leftwards arrow with hook" (U+21A9) that was being used for backlinks from citations.

I figured the font being used must not have these, so I downloaded Code2000 and verified that all three of these characters are in that font. If I set the book to use this font, characters display fine. However, the trouble comes when I try to use a different font with Code2000 as a supplemental font.

The info icon next to the Supplemental font selection says that "If a character cannot be rendered by the main font selected for the book, we try to render it using the supplemental font." However, selecting Code2000 as the supplemental font does nothing. The characters show as � or as an empty box regardless of the supplemental font chosen.

This seems like a bug to me, and not the expected behavior. Wondering if there is a fix or if anyone else has noticed this.

The book in question is a Kepub book converted with Calibre.

07-09-2026, 09:06 AM	#1
trekky0623 Enthusiast Posts: 25 Karma: 10 Join Date: Apr 2013 Device: Kindle Paperwhite	How do "Supplemental" fonts work on the Kobo I have a Kobo Clara BW running software version 4.45.23697. I have noticed many unicode characters not rendering correctly with some fonts, specifically characters like thin space (U+2009), em space (U+2003), and in one book the "leftwards arrow with hook" (U+21A9) that was being used for backlinks from citations. I figured the font being used must not have these, so I downloaded Code2000 and verified that all three of these characters are in that font. If I set the book to use this font, characters display fine. However, the trouble comes when I try to use a different font with Code2000 as a supplemental font. The info icon next to the Supplemental font selection says that "If a character cannot be rendered by the main font selected for the book, we try to render it using the supplemental font." However, selecting Code2000 as the supplemental font does nothing. The characters show as � or as an empty box regardless of the supplemental font chosen. This seems like a bug to me, and not the expected behavior. Wondering if there is a fix or if anyone else has noticed this. The book in question is a Kepub book converted with Calibre.