diff --git a/convert.go b/convert.go
index a153788..9c7c2f8 100644
--- a/convert.go
+++ b/convert.go
@@ -35,6 +35,7 @@ var superscripts = map[rune]rune{
 	'\u0038': '\u2078',
 	'\u0039': '\u2079',
 	'\u002b': '\u207a',
+	'\u002d': '\u207b',
 	'\u2212': '\u207b',
 	'\u003d': '\u207c',
 	'\u0028': '\u207d',