diff --git a/src/Errors.h b/src/Errors.h
index 50b093efc..daa105001 100644
--- a/src/Errors.h
+++ b/src/Errors.h
@@ -47,7 +47,7 @@ enum ERRORS_ALL {
 	DAT_ERR_JCLASS_TYPE, DAT_ERR_JCLASS_FIELDS, DAT_ERR_JCLASS_ANNOTATION,
 	DAT_ERR_JOBJECT_TYPE, DAT_ERR_JARRAY_TYPE, DAT_ERR_JARRAY_CONTENT,
 	/* CW map decoding errors */
-	NBT_ERR_UNKNOWN, CW_ERR_ROOT_TAG, CW_ERR_STRING_LEN,
+	NBT_ERR_UNKNOWN, CW_ERR_ROOT_TAG, CW_ERR_STRING_LEN, CW_ERR_UUID_LEN,
 	/* OpenAL initing errors */
 	AL_ERR_INIT_DEVICE, AL_ERR_INIT_CONTEXT,
 	/* Inflate errors */
diff --git a/src/Formats.c b/src/Formats.c
index b91b1749b..cc5acb6e7 100644
--- a/src/Formats.c
+++ b/src/Formats.c
@@ -259,7 +259,7 @@ cc_result Fcm_Load(struct Stream* stream) {
 
 	/* header[25] (4) date modified */
 	/* header[29] (4) date created */
-	Mem_Copy(&World.Uuid, &header[33], sizeof(World.Uuid));
+	Mem_Copy(&World.Uuid, &header[33], WORLD_UUID_LEN);
 	/* header[49] (26) layer index */
 	count = (int)Stream_GetU32_LE(&header[75]);
 
@@ -304,6 +304,7 @@ struct NbtTag {
 		struct { String text; char buffer[NBT_STRING_SIZE]; } str;
 	} value;
 	char _nameBuffer[NBT_STRING_SIZE];
+	cc_result err;
 };
 
 static cc_uint8 NbtTag_U8(struct NbtTag* tag) {
@@ -432,10 +433,11 @@ static cc_result Nbt_ReadTag(cc_uint8 typeId, cc_bool readTagName, struct Stream
 	}
 
 	if (res) return res;
+	tag.err = 0;
 	callback(&tag);
 	/* NOTE: callback must set DataBig to NULL, if doesn't want it to be freed */
 	if (!NbtTag_IsSmall(&tag)) Mem_Free(tag.value.big);
-	return 0;
+	return tag.err;
 }
 #define IsTag(tag, tagName) (String_CaselessEqualsConst(&tag->name, tagName))
 
@@ -500,8 +502,11 @@ static void Cw_Callback_1(struct NbtTag* tag) {
 	if (IsTag(tag, "Z")) { World.Length = NbtTag_U16(tag); return; }
 
 	if (IsTag(tag, "UUID")) {
-		if (tag->dataSize != sizeof(World.Uuid)) Logger_Abort("Map UUID must be 16 bytes");
-		Mem_Copy(World.Uuid, tag->value.small, sizeof(World.Uuid));
+		if (tag->dataSize != WORLD_UUID_LEN) {
+			tag->err = CW_ERR_UUID_LEN;
+		} else {
+			Mem_Copy(World.Uuid, tag->value.small, WORLD_UUID_LEN);
+		}
 		return;
 	}
 
@@ -1091,7 +1096,7 @@ cc_result Cw_Save(struct Stream* stream) {
 
 	Mem_Copy(tmp, cw_begin, sizeof(cw_begin));
 	{
-		Mem_Copy(&tmp[43], World.Uuid, sizeof(World.Uuid));
+		Mem_Copy(&tmp[43], World.Uuid, WORLD_UUID_LEN);
 		Stream_SetU16_BE(&tmp[63], World.Width);
 		Stream_SetU16_BE(&tmp[69], World.Height);
 		Stream_SetU16_BE(&tmp[75], World.Length);
diff --git a/src/World.c b/src/World.c
index 602c40cb2..4093ddaae 100644
--- a/src/World.c
+++ b/src/World.c
@@ -25,7 +25,7 @@ static void GenerateNewUuid(void) {
 		Random_Next(&rnd, Game_Username.buffer[i] + 3);
 	}
 
-	for (i = 0; i < 16; i++) {
+	for (i = 0; i < WORLD_UUID_LEN; i++) {
 		World.Uuid[i] = Random_Next(&rnd, 256);
 	}
 
diff --git a/src/World.h b/src/World.h
index 706516b74..4606aba25 100644
--- a/src/World.h
+++ b/src/World.h
@@ -12,6 +12,7 @@ struct AABB;
 #define World_Unpack(idx, x, y, z) x = idx % World.Width; z = (idx / World.Width) % World.Length; y = (idx / World.Width) / World.Length;
 /* Packs an x,y,z into a single index */
 #define World_Pack(x, y, z) (((y) * World.Length + (z)) * World.Width + (x))
+#define WORLD_UUID_LEN 16
 
 CC_VAR extern struct _WorldData {
 	/* The blocks in the world. */
@@ -32,7 +33,7 @@ CC_VAR extern struct _WorldData {
 	/* Adds one Y coordinate to a packed index. */
 	int OneY;
 	/* Unique identifier for this world. */
-	cc_uint8 Uuid[16];
+	cc_uint8 Uuid[WORLD_UUID_LEN];
 
 #ifdef EXTENDED_BLOCKS
 	/* Masks access to World.Blocks/World.Blocks2 */