diff --git a/Doc/lib/libstrings.tex b/Doc/lib/libstrings.tex
index ea9a099966d..ec4834b8c41 100644
--- a/Doc/lib/libstrings.tex
+++ b/Doc/lib/libstrings.tex
@@ -17,4 +17,7 @@ manipulation operations.  Here's an overview:
 \item[struct]
 --- Interpret strings as packed binary data.
 
+\item[StringIO]
+--- Read and write strings as if they were files.
+
 \end{description}
diff --git a/Doc/libstrings.tex b/Doc/libstrings.tex
index ea9a099966d..ec4834b8c41 100644
--- a/Doc/libstrings.tex
+++ b/Doc/libstrings.tex
@@ -17,4 +17,7 @@ manipulation operations.  Here's an overview:
 \item[struct]
 --- Interpret strings as packed binary data.
 
+\item[StringIO]
+--- Read and write strings as if they were files.
+
 \end{description}