diff --git a/src/dog.c b/src/dog.c
index 361c7de02..a5f8a5a75 100644
--- a/src/dog.c
+++ b/src/dog.c
@@ -325,7 +325,7 @@ boolean with_you;
     xyflags = mtmp->mtrack[0].y;
     xlocale = mtmp->mtrack[1].x;
     ylocale = mtmp->mtrack[1].y;
-    memset(mtmp->mtrack, MTSZ, sizeof(coord));
+    memset(mtmp->mtrack, 0, sizeof(mtmp->mtrack));
 
     if (mtmp == u.usteed)
         return; /* don't place steed on the map */
diff --git a/src/monmove.c b/src/monmove.c
index cae22b8b5..86432a6c5 100644
--- a/src/monmove.c
+++ b/src/monmove.c
@@ -272,7 +272,7 @@ boolean fleemsg;
         mtmp->mflee = 1;
     }
     /* ignore recently-stepped spaces when made to flee */
-    memset(mtmp->mtrack, MTSZ, sizeof(coord));
+    memset(mtmp->mtrack, 0, sizeof(mtmp->mtrack));
 }
 
 STATIC_OVL void
diff --git a/src/teleport.c b/src/teleport.c
index 47780e7da..43e97da63 100644
--- a/src/teleport.c
+++ b/src/teleport.c
@@ -980,7 +980,7 @@ register int x, y;
         }
     }
 
-    memset(mtmp->mtrack, MTSZ, sizeof(coord));
+    memset(mtmp->mtrack, 0, sizeof(mtmp->mtrack));
     place_monster(mtmp, x, y); /* put monster down */
     update_monster_region(mtmp);