--- a/newgrf.c	Fri Dec 15 18:51:47 2006 +0000
+++ b/newgrf.c	Mon Dec 18 10:46:06 2006 +0000
@@ -1843,6 +1843,11 @@
 				if (ctype == 0xFE) ctype = GC_DEFAULT_NA;
 				if (ctype == 0xFF) ctype = GC_PURCHASE;
 
+				if (ctype >= NUM_GLOBAL_CID) {
+					grfmsg(GMS_WARN, "FeatureMapSpriteGroup: Cargo type %d out of range, skipping.", ctype);
+					continue;
+				}
+
 				statspec->spritegroup[ctype] = _cur_grffile->spritegroups[groupid];
 			}
 		}
@@ -1919,6 +1924,11 @@
 
 			if (ctype == GC_INVALID) ctype = GC_PURCHASE;
 
+			if (ctype >= NUM_GLOBAL_CID) {
+				grfmsg(GMS_WARN, "FeatureMapSpriteGroup: Cargo type %d out of range, skipping.", ctype);
+				continue;
+			}
+
 			if (wagover) {
 				SetWagonOverrideSprites(engine, ctype, _cur_grffile->spritegroups[groupid], last_engines, last_engines_count);
 			} else {

--- a/newgrf_engine.c	Fri Dec 15 18:51:47 2006 +0000
+++ b/newgrf_engine.c	Mon Dec 18 10:46:06 2006 +0000
@@ -77,6 +77,9 @@
 	WagonOverrides *wos;
 	WagonOverride *wo;
 
+	assert(engine < TOTAL_NUM_ENGINES);
+	assert(cargo < NUM_GLOBAL_CID);
+
 	wos = &_engine_wagon_overrides[engine];
 	wos->overrides_count++;
 	wos->overrides = realloc(wos->overrides,
@@ -147,6 +150,8 @@
 void SetCustomEngineSprites(EngineID engine, byte cargo, const SpriteGroup *group)
 {
 	assert(engine < TOTAL_NUM_ENGINES);
+	assert(cargo < NUM_GLOBAL_CID);
+
 	if (engine_custom_sprites[engine][cargo] != NULL) {
 		DEBUG(grf, 6)("SetCustomEngineSprites: engine `%d' cargo `%d' already has group -- replacing.", engine, cargo);
 	}