diff --git a/Doc/ref/ref3.tex b/Doc/ref/ref3.tex
index e1c6048a5b2..e522b82e4a1 100644
--- a/Doc/ref/ref3.tex
+++ b/Doc/ref/ref3.tex
@@ -123,7 +123,7 @@ It is used to signify the absence of a value in many situations, e.g.,
 it is returned from functions that don't explicitly return anything.
 Its truth value is false.
 \ttindex{None}
-\obindex{None@{\tt None}}
+\obindex{None@{\texttt{None}}}
 
 \item[Ellipsis]
 This type has a single value.  There is a single object with this value.
@@ -131,7 +131,7 @@ This object is accessed through the built-in name \code{Ellipsis}.
 It is used to indicate the presence of the \samp{...} syntax in a
 slice.  Its truth value is true.
 \ttindex{Ellipsis}
-\obindex{Ellipsis@{\tt Ellipsis}}
+\obindex{Ellipsis@{\texttt{Ellipsis}}}
 
 \item[Numbers]
 These are created by numeric literals and returned as results by