diff --git a/Doc/Makefile b/Doc/Makefile
index 98f7f61cbbe..b72faa30bfa 100644
--- a/Doc/Makefile
+++ b/Doc/Makefile
@@ -110,7 +110,8 @@ LIBFILES = lib.tex \
     libformatter.tex liboperator.tex libsoundex.tex libresource.tex \
     libstat.tex libstrio.tex libundoc.tex libmailcap.tex libglob.tex \
     libuser.tex libanydbm.tex librandom.tex libsite.tex libwhichdb.tex \
-    libbase64.tex libfnmatch.tex libquopri.tex libzlib.tex libsocksvr.tex
+    libbase64.tex libfnmatch.tex libquopri.tex libzlib.tex libsocksvr.tex \
+    libmailbox.tex
 
 # Library document
 lib.dvi: $(LIBFILES)