diff --git a/packages/font-glyphs/src/letter/latin/upper-b.ptl b/packages/font-glyphs/src/letter/latin/upper-b.ptl
index ab58caf27..c7ea773c3 100644
--- a/packages/font-glyphs/src/letter/latin/upper-b.ptl
+++ b/packages/font-glyphs/src/letter/latin/upper-b.ptl
@@ -225,14 +225,18 @@ glyph-block Letter-Latin-Upper-B : begin
 
 	create-glyph 'mathbb/B' 0x1D539 : glyph-proc
 		include : MarkSet.capital
-		include : union
-			BShape CAP (stroke -- BBS) (serifs -- false)
-			intersection
-				BShapeMask CAP (stroke -- BBS)
-				union
-					VBar.r (RightSB - BBD - OX * 2) 0 (CAP * BBarPos) BBS
-					VBar.r ([mix SB RightSB BArcMix] - BBD - OX * 2) (CAP * BBarPos) CAP BBS
-					VBar.l (SB + BBD) 0 CAP BBS
+		include : difference
+			union
+				BShape CAP (stroke -- BBS) (serifs -- false)
+				intersection
+					BShapeMask CAP (stroke -- BBS)
+					union
+						VBar.r (RightSB - BBD - OX * 2) 0 (CAP * BBarPos) BBS
+						VBar.r ([mix SB RightSB BArcMix] - BBD - OX * 2) (CAP * BBarPos) CAP BBS
+						VBar.l (SB + BBD) 0 CAP BBS
+			Rect (CAP - BBS) (0 + BBS) (SB + [HSwToV BBS]) (SB + BBD)
+
+	### Greek Beta
 
 	create-glyph 'grek/beta.standard' : glyph-proc
 		include : MarkSet.bp