diff --git a/Doc/lib/libfcntl.tex b/Doc/lib/libfcntl.tex
index 15aeec28ca46..5dab2838dc8a 100644
--- a/Doc/lib/libfcntl.tex
+++ b/Doc/lib/libfcntl.tex
@@ -1,8 +1,8 @@
 % Manual text by Jaap Vermeulen
 \section{Built-in Module \sectcode{fcntl}}
 \bimodindex{fcntl}
-\indexii{\UNIX{}}{file control}
-\indexii{\UNIX{}}{I/O control}
+\indexii{UNIX@\UNIX{}}{file control}
+\indexii{UNIX@\UNIX{}}{I/O control}
 
 This module performs file control and I/O control on file descriptors.
 It is an interface to the \dfn{fcntl()} and \dfn{ioctl()} \UNIX{} routines.
diff --git a/Doc/libfcntl.tex b/Doc/libfcntl.tex
index 15aeec28ca46..5dab2838dc8a 100644
--- a/Doc/libfcntl.tex
+++ b/Doc/libfcntl.tex
@@ -1,8 +1,8 @@
 % Manual text by Jaap Vermeulen
 \section{Built-in Module \sectcode{fcntl}}
 \bimodindex{fcntl}
-\indexii{\UNIX{}}{file control}
-\indexii{\UNIX{}}{I/O control}
+\indexii{UNIX@\UNIX{}}{file control}
+\indexii{UNIX@\UNIX{}}{I/O control}
 
 This module performs file control and I/O control on file descriptors.
 It is an interface to the \dfn{fcntl()} and \dfn{ioctl()} \UNIX{} routines.