diff --git a/ctanks.c b/ctanks.c
index f7d1049..7d7c7c5 100644
--- a/ctanks.c
+++ b/ctanks.c
@@ -116,13 +116,14 @@ tanks_fire_cannon(struct tanks_game *game,
   float theta = this->angle + this->turret.current;
   float rpos[2];
 
-  /* If someone's a crater, this is easy */
-  if (this->killer || that->killer) {
+  /* If someone's a crater, this is easy (unless we were just killed by the other one, in which case
+     we have to check the other direction) */
+  if ((this->killer && this->killer != that) || that->killer) {
     return;
   }
 
   /* Did they collide? */
-  if (dist2 < TANK_COLLISION_ADJ2) {
+  if ((!this->killer) && dist2 < TANK_COLLISION_ADJ2) {
     this->killer = that;
     this->cause_death = "collision";
 
diff --git a/forf.c b/forf.c
index 18e950d..b85de82 100644
--- a/forf.c
+++ b/forf.c
@@ -30,6 +30,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <limits.h>
 
 #include "forf.h"
 #include "dump.h"
@@ -348,7 +349,7 @@ forf_proc_div(struct forf_env *env)
   long a = forf_pop_num(env);
   long b = forf_pop_num(env);
 
-  if (0 == a) {
+  if (0 == a || (a == -1 && b == LONG_MIN)) {
     env->error = forf_error_divzero;
     return;
   }
@@ -361,7 +362,7 @@ forf_proc_mod(struct forf_env *env)
   long a = forf_pop_num(env);
   long b = forf_pop_num(env);
 
-  if (0 == a) {
+  if (0 == a || (a == -1 && b == LONG_MIN)) {
     env->error = forf_error_divzero;
     return;
   }