diff --git a/Doc/lib/libstring.tex b/Doc/lib/libstring.tex
index c11aaa56013..e95741eb8c3 100644
--- a/Doc/lib/libstring.tex
+++ b/Doc/lib/libstring.tex
@@ -10,7 +10,7 @@ classes and some useful string functions.  See the module
 \refmodule{re}\refstmodindex{re} for string functions based on regular
 expressions.
 
-The constants defined in this module are are:
+The constants defined in this module are:
 
 \begin{datadesc}{digits}
   The string \code{'0123456789'}.