--- papersize.tmac	2022-11-16 11:56:45.088890965 -0500
+++ papersize-mommified.tmac	2022-11-16 11:56:54.359054026 -0500
@@ -151,9 +151,12 @@
 .
 .  ie \n[paper-w] \
 .    tm warning: Unknown paper size '\*[paper]'
-.  el \
+.  el \{\
 .    if !r LL \
 .      nr LL \n[.l]u  \" for ms, mdoc, man
+.    if !r #R_MARGIN \
+.      R_MARGIN 1i \" for mom
+.  \}
 .\}
 .
 .cp \n[_C]