diff --git a/Doc/lib/libsys.tex b/Doc/lib/libsys.tex
index ff5d65e9f5b..32f6699cd26 100644
--- a/Doc/lib/libsys.tex
+++ b/Doc/lib/libsys.tex
@@ -19,7 +19,7 @@ It is always available.
 \end{datadesc}
 
 \begin{datadesc}{builtin_module_names}
-  A list of strings giving the names of all modules that are compiled
+  A tuple of strings giving the names of all modules that are compiled
   into this Python interpreter.  (This information is not available in
   any other way --- \code{sys.modules.keys()} only lists the imported
   modules.)
diff --git a/Doc/libsys.tex b/Doc/libsys.tex
index ff5d65e9f5b..32f6699cd26 100644
--- a/Doc/libsys.tex
+++ b/Doc/libsys.tex
@@ -19,7 +19,7 @@ It is always available.
 \end{datadesc}
 
 \begin{datadesc}{builtin_module_names}
-  A list of strings giving the names of all modules that are compiled
+  A tuple of strings giving the names of all modules that are compiled
   into this Python interpreter.  (This information is not available in
   any other way --- \code{sys.modules.keys()} only lists the imported
   modules.)