diff --git a/attack.cpp b/attack.cpp
index d9f80c59..088897bf 100644
--- a/attack.cpp
+++ b/attack.cpp
@@ -1211,7 +1211,7 @@ EX void stabbingAttack(movei mi, eMonster who, int bonuskill IS(0)) {
 
   cell *mf = mi.s;
   cell *mt = mi.t;
-  int backdir = mi.rev_dir();
+  int backdir = mi.rev_dir_mirror();
   
   do_swords(mi, who, [&] (cell *c, int bb) { if(swordAttack(mt, who, c, bb)) numbb[bb]++, numslash++; });
   
@@ -1279,7 +1279,7 @@ EX void stabbingAttack(movei mi, eMonster who, int bonuskill IS(0)) {
     if(!logical_adjacent(mt, who, c)) continue;
     eMonster mm = c->monst;
     int flag = AF_APPROACH;
-    if(anglestraight(mt, backdir, t)) flag |= AF_HORNS;
+    if(proper(mt, backdir) && anglestraight(mt, backdir, t)) flag |= AF_HORNS;
     if(canAttack(mt,who,c,c->monst, flag)) {
       changes.ccell(c);
       if(attackMonster(c, flag | AF_MSG, who)) numlance++;
diff --git a/complex.cpp b/complex.cpp
index 937f1abd..8368b6aa 100644
--- a/complex.cpp
+++ b/complex.cpp
@@ -2872,7 +2872,7 @@ EX namespace sword {
     cell *c2 = mi.t;
     if(!mi.proper()) return d;
     int s1 = mi.d;
-    int s2 = mi.rev_dir();
+    int s2 = mi.rev_dir_force();
     neighborId(c2, c1);
     if(s1 < 0 || s2 < 0) return d;
     if(SWORDDIM == 2) {
diff --git a/locations.cpp b/locations.cpp
index e52e3cb5..7b1aaf8f 100644
--- a/locations.cpp
+++ b/locations.cpp
@@ -452,6 +452,8 @@ inline cellwalker operator+ (heptspin hs, cth_t) { return cellwalker(hs.at->c7,
 
 #endif
 
+EX bool proper(cell *c, int d) { return d >= 0 && d < c->type; }
+
 #if HDR
 
 constexpr int STRONGWIND = 99;
@@ -485,7 +487,8 @@ struct movei {
   movei rev() const { return movei(t, s, rev_dir_or(d)); }
   int dir_or(int x) const { return proper() ? d : x; }
   int rev_dir_or(int x) const { return proper() ? s->c.spin(d) : x; }
-  int rev_dir() const { return s->c.spin(d); }
+  int rev_dir_mirror() const { return proper() ? s->c.spin(d) : d; }
+  int rev_dir_force() const { hassert(proper()); return s->c.spin(d); }
   bool mirror() { return s->c.mirror(d); }
   };
 #endif
diff --git a/monstermove.cpp b/monstermove.cpp
index 661113cd..e4545817 100644
--- a/monstermove.cpp
+++ b/monstermove.cpp
@@ -765,12 +765,12 @@ EX void mountmove(const movei& mi, bool fp) {
       animateMovement(mi, LAYER_SMALL);
       if(multi::players > 1) {
         multi::player[i].at = mi.t;
-        multi::player[i].spin = mi.rev_dir();
+        multi::player[i].spin = mi.rev_dir_force();
         multi::flipped[i] = fp;
         }
       else {
         cwt.at = mi.t;
-        cwt.spin = mi.rev_dir();
+        cwt.spin = mi.rev_dir_force();
         flipplayer = fp;
         }
       afterplayermoved();