diff --git a/src/mhitm.c b/src/mhitm.c
index 8892c0f59..39fe251a7 100644
--- a/src/mhitm.c
+++ b/src/mhitm.c
@@ -284,6 +284,9 @@ mdisplacem(
  * Each successive attack has a lower probability of hitting.  Some rely on
  * success of previous attacks.  ** this doesn't seem to be implemented -dl **
  *
+ * Attacker has targeted <bhitpos.x,bhitpos.y> rather than
+ * <mdef->mx,mdef->my>; matters for long worms.
+ *
  * In the case of exploding monsters, the monster dies as well.
  */
 int
@@ -353,7 +356,7 @@ mattackm(
 
     /* Set up the visibility of action */
     gv.vis = ((cansee(magr->mx, magr->my) && canspotmon(magr))
-             || (cansee(mdef->mx, mdef->my) && canspotmon(mdef)));
+              || (cansee(mdef->mx, mdef->my) && canspotmon(mdef)));
 
     /* Set flag indicating monster has moved this turn.  Necessary since a
      * monster might get an attack out of sequence (i.e. before its move) in
@@ -371,6 +374,12 @@ mattackm(
     /* Now perform all attacks for the monster. */
     for (i = 0; i < NATTK; i++) {
         res[i] = M_ATTK_MISS;
+
+        /* target might no longer be there */
+        if (i > 0 && (m_at(gb.bhitpos.x, gb.bhitpos.y) != mdef
+                      || DEADMONSTER(magr) || DEADMONSTER(mdef)))
+            continue;
+
         mattk = getmattk(magr, mdef, i, res, &alt_attk);
         /* reduce verbosity for mind flayer attacking creature without a
            head (or worm's tail); this is similar to monster with multiple
diff --git a/src/mhitu.c b/src/mhitu.c
index ed0b6e098..0357915e8 100644
--- a/src/mhitu.c
+++ b/src/mhitu.c
@@ -754,6 +754,8 @@ mattacku(struct monst *mtmp)
             /* if hero was found but isn't anymore, avoid wildmiss now */
             if (firstfoundyou && !foundyou)
                 continue; /* set sum[i] to 'miss' but skip other actions */
+            if (!u_at(gb.bhitpos.x, gb.bhitpos.y))
+                continue;
         }
         mon_currwep = (struct obj *) 0;
         mattk = getmattk(mtmp, &gy.youmonst, i, sum, &alt_attk);
diff --git a/src/uhitm.c b/src/uhitm.c
index 56a4079ce..90014bcd6 100644
--- a/src/uhitm.c
+++ b/src/uhitm.c
@@ -5203,7 +5203,7 @@ mhitm_knockback(
     boolean u_def = (mdef == &gy.youmonst);
     boolean was_u = FALSE, dismount = FALSE;
     struct obj *wep = weapon_used ? (u_agr ? uwep : MON_WEP(magr))
-                                  : (struct obj *)0;
+                                  : (struct obj *) 0;
 
     if (wep && is_art(wep, ART_OGRESMASHER))
         chance = 2;
@@ -5211,6 +5211,20 @@ mhitm_knockback(
     if (rn2(chance))
         return FALSE;
 
+    /* only certain attacks qualify for knockback */
+    if (!((mattk->adtyp == AD_PHYS)
+          && (mattk->aatyp == AT_CLAW
+              || mattk->aatyp == AT_KICK
+              || mattk->aatyp == AT_BUTT
+              || mattk->aatyp == AT_WEAP)))
+        return FALSE;
+
+    /* don't knockback if attacker also wants to grab or engulf */
+    if (attacktype(magr->data, AT_ENGL)
+        || attacktype(magr->data, AT_HUGS)
+        || sticks(magr->data))
+        return FALSE;
+
     /* decide where the first step will place the target; not accurate
        for being knocked out of saddle but doesn't need to be; used for
        test_move() and for message before actual hurtle */
@@ -5257,14 +5271,6 @@ mhitm_knockback(
     if (wep && (is_flimsy(wep) || !is_blunt_weapon(wep)))
         return FALSE;
 
-    /* only certain attacks qualify for knockback */
-    if (!((mattk->adtyp == AD_PHYS)
-          && (mattk->aatyp == AT_CLAW
-              || mattk->aatyp == AT_KICK
-              || mattk->aatyp == AT_BUTT
-              || mattk->aatyp == AT_WEAP)))
-        return FALSE;
-
     /* needs a solid physical hit */
     if (unsolid(magr->data))
         return FALSE;
@@ -5388,6 +5394,14 @@ hmonas(struct monst *mon)
 
     for (i = 0; i < NATTK; i++) {
         /* sum[i] = M_ATTK_MISS; -- now done above */
+
+        /* target might have been knocked back so no longer in range, or an
+           engulfing vampshifted fog cloud killed and reverted to vampire
+           that's placed at another spot (hero occupies mon's first spot) */
+        if (i > 0 && (m_at(gb.bhitpos.x, gb.bhitpos.y) != mon
+                      || DEADMONSTER(mon)))
+            continue;
+
         mattk = getmattk(&gy.youmonst, mon, i, sum, &alt_attk);
         if (gs.skipdrin && mattk->aatyp == AT_TENT && mattk->adtyp == AD_DRIN)
             continue;