diff --git a/unpacked/jax/input/TeX/jax.js b/unpacked/jax/input/TeX/jax.js
index eba0538ad..d173a57c9 100644
--- a/unpacked/jax/input/TeX/jax.js
+++ b/unpacked/jax/input/TeX/jax.js
@@ -801,7 +801,7 @@
         nolimits:          ['Limits',0],
 
         overline:            ['UnderOver','00AF',null,1],
-        underline:           ['UnderOver','005F',null,1],
+        underline:           ['UnderOver','005F'],
         overbrace:           ['UnderOver','23DE',1],
         underbrace:          ['UnderOver','23DF',1],
         overparen:           ['UnderOver','23DC'],