diff --git a/src/servers/app/font/FontCacheEntry.cpp b/src/servers/app/font/FontCacheEntry.cpp
index 953a12bae9..ef8af33af3 100644
--- a/src/servers/app/font/FontCacheEntry.cpp
+++ b/src/servers/app/font/FontCacheEntry.cpp
@@ -202,8 +202,6 @@ render_as_space(uint32 glyphCode)
 			// no-break space
 		|| (glyphCode == 0x1680)
 			// ogham space mark
-		|| (glyphCode == 0x180e)
-			// mongolian vowel separator
 		|| (glyphCode >= 0x2000 && glyphCode <= 0x200a)
 			// en quand, hair space
 		|| (glyphCode >= 0x2028 && glyphCode <= 0x2029)
@@ -222,17 +220,20 @@ inline bool
 render_as_zero_width(uint32 glyphCode)
 {
 	// ignorable chars: render as invisible
-	// as per Unicode DerivedCoreProperties.txt: Default_Ignorable_Code_Point
+	// as per Unicode DerivedCoreProperties.txt: Default_Ignorable_Code_Point.
+	// We also don't want tofu for noncharacters if we ever get one.
 	return (glyphCode == 0x00ad)
 			// soft hyphen
 		|| (glyphCode == 0x034f)
 			// combining grapheme joiner
+		|| (glyphCode == 0x061c)
+			// arabic letter mark
 		|| (glyphCode >= 0x115f && glyphCode <= 0x1160)
 			// hangul fillers
 		|| (glyphCode >= 0x17b4 && glyphCode <= 0x17b5)
 			// ignorable khmer vowels
-		|| (glyphCode >= 0x180b && glyphCode <= 0x180d)
-			// variation selectors
+		|| (glyphCode >= 0x180b && glyphCode <= 0x180f)
+			// mongolian variation selectors and vowel separator
 		|| (glyphCode >= 0x200b && glyphCode <= 0x200f)
 			// zero width space, cursive joiners, ltr marks
 		|| (glyphCode >= 0x202a && glyphCode <= 0x202e)
@@ -249,10 +250,19 @@ render_as_zero_width(uint32 glyphCode)
 			// halfwidth hangul filler
 		|| (glyphCode >= 0xfff0 && glyphCode <= 0xfff8)
 			// reserved
+		|| (glyphCode >= 0x1bca0 && glyphCode <= 0x1bca3)
+			// shorthand format controls
 		|| (glyphCode >= 0x1d173 && glyphCode <= 0x1d17a)
 			// musical symbols
 		|| (glyphCode >= 0xe0000 && glyphCode <= 0xe01ef)
 			// variation selectors, tag space, reserved
+		|| (glyphCode >= 0xe01f0 && glyphCode <= 0xe0fff)
+			// reserved
+		|| ((glyphCode & 0xffff) >= 0xfffe)
+			// noncharacters
+		|| ((glyphCode >= 0xfdd0 && glyphCode <= 0xfdef)
+			&& glyphCode != 0xfdd1)
+			// noncharacters; 0xfdd1 is used internally to force .notdef glyph
 		;
 }