diff --git a/docs/cmu-user/extensions.tex b/docs/cmu-user/extensions.tex
index a3c7b53efebb75400fe592a050885623f2cfa909..0efb2f3b9ee6790af98686fafb6f282193789cbc 100644
--- a/docs/cmu-user/extensions.tex
+++ b/docs/cmu-user/extensions.tex
@@ -1775,7 +1775,7 @@ website at
 \section{Lisp Threads}
 \cindex{lisp threads}
 
-\cmucl supports Lisp threads for the x86 platform.
+\cmucl{} supports Lisp threads for the x86 platform.
 
 \section{Lisp Library}
 \label{lisp-lib}