diff --git a/polymer/eduke32/source/game.h b/polymer/eduke32/source/game.h
index 95e2505c9..81aa64436 100644
--- a/polymer/eduke32/source/game.h
+++ b/polymer/eduke32/source/game.h
@@ -334,7 +334,8 @@ extern char forcegl;
 #define gametextpal(x,y,t,s,p) G_PrintGameText(0,STARTALPHANUM, x,y,t,s,p,26,0, 0, xdim-1, ydim-1, 65536)
 #define gametextpalbits(x,y,t,s,p,dabits) G_PrintGameText(0,STARTALPHANUM, x,y,t,s,p,dabits,0, 0, xdim-1, ydim-1, 65536)
 #define A_CheckSpriteFlags(iActor, iType) (((SpriteFlags[sprite[iActor].picnum]^actor[iActor].flags) & iType) != 0)
-#define A_CheckSpriteTileFlags(iPicnum, iType) ((SpriteFlags[iPicnum] & iType) != 0)
+// (unsigned)iPicnum check: AMC TC Rusty Nails, bayonet MG alt. fire, iPicnum == -1 (via aplWeaponShoots)
+#define A_CheckSpriteTileFlags(iPicnum, iType) (((unsigned)iPicnum < MAXTILES) && (SpriteFlags[iPicnum] & iType) != 0)
 #define G_EnterText(x, y, t, dalen, c) _EnterText(0,x,y,t,dalen,c)
 #define Net_EnterText(x, y, t, dalen, c) _EnterText(1,x,y,t,dalen,c)
 #define S_StopSound(num) S_StopEnvSound(num, -1)
diff --git a/polymer/eduke32/source/gamevars.c b/polymer/eduke32/source/gamevars.c
index 2accf45a1..55298f29f 100644
--- a/polymer/eduke32/source/gamevars.c
+++ b/polymer/eduke32/source/gamevars.c
@@ -932,6 +932,8 @@ void Gv_ResetSystemDefaults(void)
             aplWeaponFlags[i][j]=Gv_GetVarByLabel(aszBuf,0, -1, j);
             Bsprintf(aszBuf,"WEAPON%d_SHOOTS",i);
             aplWeaponShoots[i][j]=Gv_GetVarByLabel(aszBuf,0, -1, j);
+            if ((unsigned)aplWeaponShoots[i][j] >= MAXTILES)
+                aplWeaponShoots[i][j] = 0;
             Bsprintf(aszBuf,"WEAPON%d_SPAWNTIME",i);
             aplWeaponSpawnTime[i][j]=Gv_GetVarByLabel(aszBuf,0, -1, j);
             Bsprintf(aszBuf,"WEAPON%d_SPAWN",i);
diff --git a/polymer/eduke32/source/player.c b/polymer/eduke32/source/player.c
index 7c206694b..8df47203c 100644
--- a/polymer/eduke32/source/player.c
+++ b/polymer/eduke32/source/player.c
@@ -346,26 +346,27 @@ int32_t A_Shoot(int32_t i,int32_t atwith)
         }
 
 #ifdef POLYMER
-        switch (DynamicTileMap[atwith])
-        {
-        case FIRELASER__STATIC:
-        case SHOTGUN__STATIC:
-        case SHOTSPARK1__STATIC:
-        case CHAINGUN__STATIC:
-        case RPG__STATIC:
-        case MORTER__STATIC:
-        {
-            int32_t x = ((sintable[(s->ang+512)&2047])>>7), y = ((sintable[(s->ang)&2047])>>7);
-            s-> x += x;
-            s-> y += y;
-            G_AddGameLight(0, i, PHEIGHT, 8192, 255+(95<<8),PR_LIGHT_PRIO_MAX_GAME);
-            actor[i].lightcount = 2;
-            s-> x -= x;
-            s-> y -= y;
-        }
+        if (atwith >= 0)
+            switch (DynamicTileMap[atwith])
+            {
+            case FIRELASER__STATIC:
+            case SHOTGUN__STATIC:
+            case SHOTSPARK1__STATIC:
+            case CHAINGUN__STATIC:
+            case RPG__STATIC:
+            case MORTER__STATIC:
+            {
+                int32_t x = ((sintable[(s->ang+512)&2047])>>7), y = ((sintable[(s->ang)&2047])>>7);
+                s-> x += x;
+                s-> y += y;
+                G_AddGameLight(0, i, PHEIGHT, 8192, 255+(95<<8),PR_LIGHT_PRIO_MAX_GAME);
+                actor[i].lightcount = 2;
+                s-> x -= x;
+                s-> y -= y;
+            }
 
-        break;
-        }
+            break;
+            }
 #endif // POLYMER
     }
 
@@ -1044,7 +1045,7 @@ DOSKIPBULLETHOLE:
         }
 
     }
-    else
+    else if (atwith >= 0)
     {
         switch (DynamicTileMap[atwith])
         {