diff --git a/Doc/lib/libsys.tex b/Doc/lib/libsys.tex
index e16fbd56868..2ea4c379ac6 100644
--- a/Doc/lib/libsys.tex
+++ b/Doc/lib/libsys.tex
@@ -28,6 +28,7 @@ every 10 Python virtual instructions.  Setting this to a large value
 may increase performance for programs using threads.  Setting it to a
 value <= 0 checks every virtual instruction, maximizing responsiveness
 as well as overhead.
+\end{datadesc}
 
 \begin{datadesc}{exc_type}
 \dataline{exc_value}
diff --git a/Doc/libsys.tex b/Doc/libsys.tex
index e16fbd56868..2ea4c379ac6 100644
--- a/Doc/libsys.tex
+++ b/Doc/libsys.tex
@@ -28,6 +28,7 @@ every 10 Python virtual instructions.  Setting this to a large value
 may increase performance for programs using threads.  Setting it to a
 value <= 0 checks every virtual instruction, maximizing responsiveness
 as well as overhead.
+\end{datadesc}
 
 \begin{datadesc}{exc_type}
 \dataline{exc_value}