diff --git a/src/monmove.c b/src/monmove.c
index b72353629..324eaeb05 100644
--- a/src/monmove.c
+++ b/src/monmove.c
@@ -1,4 +1,4 @@
-/* NetHack 3.6	monmove.c	$NHDT-Date: 1575245074 2019/12/02 00:04:34 $  $NHDT-Branch: NetHack-3.6 $:$NHDT-Revision: 1.116 $ */
+/* NetHack 3.6	monmove.c	$NHDT-Date: 1579616424 2020/01/21 14:20:24 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.128 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /*-Copyright (c) Michael Allison, 2006. */
 /* NetHack may be freely redistributed.  See license for details. */
@@ -1286,20 +1286,27 @@ register int after;
         if (!m_in_out_region(mtmp, nix, niy))
             return 3;
 
+        /* move a normal monster; for a long worm, remove_monster() and
+           place_monster() only manipulate the head; they leave tail as-is */
         remove_monster(omx, omy);
         place_monster(mtmp, nix, niy);
+        /* for a long worm, insert a new segment to reconnect the head
+           with the tail; worm_move() keeps the end of the tail if worm
+           is scheduled to grow, removes that for move-without-growing */
+        if (mtmp->wormno)
+            worm_move(mtmp);
+
         for (j = MTSZ - 1; j > 0; j--)
             mtmp->mtrack[j] = mtmp->mtrack[j - 1];
         mtmp->mtrack[0].x = omx;
         mtmp->mtrack[0].y = omy;
-        /* Place a segment at the old position. */
-        if (mtmp->wormno)
-            worm_move(mtmp);
     } else {
         if (is_unicorn(ptr) && rn2(2) && !tele_restrict(mtmp)) {
             (void) rloc(mtmp, TRUE);
             return 1;
         }
+        /* for a long worm, shrink it (by discarding end of tail) when
+           it has failed to move */
         if (mtmp->wormno)
             worm_nomove(mtmp);
     }
diff --git a/src/worm.c b/src/worm.c
index 3d7fb3f93..c5395cbe9 100644
--- a/src/worm.c
+++ b/src/worm.c
@@ -1,4 +1,4 @@
-/* NetHack 3.6	worm.c	$NHDT-Date: 1561340880 2019/06/24 01:48:00 $  $NHDT-Branch: NetHack-3.6 $:$NHDT-Revision: 1.30 $ */
+/* NetHack 3.6	worm.c	$NHDT-Date: 1579616437 2020/01/21 14:20:37 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.40 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /*-Copyright (c) Robert Patrick Rankin, 2009. */
 /* NetHack may be freely redistributed.  See license for details. */
@@ -218,6 +218,13 @@ struct monst *worm;
     seg->nseg = new_seg;    /* attach it to the end of the list */
     wheads[wnum] = new_seg; /* move the end pointer */
 
+    /*
+     * [maybe] FIXME?
+     *  scheduling wgrowtime[] seems to be based on normal movement
+     *  speed (12) but long worms move at 1/4 of that (3), so they'll
+     *  reach the scheduled 'moves' more quickly (in terms of their
+     *  actual movement) and grow faster than was probably intended.
+     */
     if (wgrowtime[wnum] <= g.moves) {
         if (!wgrowtime[wnum])
             wgrowtime[wnum] = g.moves + rnd(5);