diff --git a/schemsearch-lib/src/nbt_search.rs b/schemsearch-lib/src/nbt_search.rs
index 9fda1b0..f370ae0 100755
--- a/schemsearch-lib/src/nbt_search.rs
+++ b/schemsearch-lib/src/nbt_search.rs
@@ -7,7 +7,9 @@ use schemsearch_files::SpongeSchematic;
 const NBT_BLOCKS: &str = include_str!("blocks.txt");
 
 lazy_static! {
-    static ref NBT_BLOCKS_SET: HashSet<String> = NBT_BLOCKS.lines().map(ToOwned::to_owned).collect();
+    static ref NBT_BLOCKS_SET: HashSet<String> = {
+        NBT_BLOCKS.lines().map(|x| format!("minecraft:{}", x)).collect()
+    };
 }
 
 pub fn has_invalid_nbt(schem: SpongeSchematic) -> bool {
@@ -15,13 +17,94 @@ pub fn has_invalid_nbt(schem: SpongeSchematic) -> bool {
         return true;
     }
 
-    let nbt_blocks = schem.palette.iter().filter(|(k, _)| NBT_BLOCKS_SET.contains(*k)).map(|(_, v)| *v).collect::<HashSet<i32>>();
+    let nbt_blocks = schem.palette.iter().filter(|(k, _)| NBT_BLOCKS_SET.contains(k.to_owned())).map(|(_, v)| *v).collect::<HashSet<i32>>();
 
-    for block_entity in schem.block_data.iter() {
-        if nbt_blocks.contains(block_entity) {
-            return true;
+    for (i, block_entity) in schem.block_data.iter().enumerate() {
+        if nbt_blocks.contains(&*block_entity) {
+            // i = x + z * Width + y * Width * Length
+            let x = i % schem.width as usize;
+            let z = (i / schem.width as usize) % schem.length as usize;
+            let y = i / (schem.width as usize * schem.length as usize);
+            if schem.block_entities.iter().any(|e| !e.pos.eq(&[x as i32, y as i32, z as i32])) {
+                return true;
+            }
         }
     }
 
     return false;
+}
+
+#[allow(unused_imports)]
+#[cfg(test)]
+mod tests {
+    use nbt::CompoundTag;
+    use schemsearch_files::{BlockEntity, SpongeSchematic};
+    use super::*;
+
+    #[test]
+    fn test_has_invalid_nbt() {
+        let schem = SpongeSchematic {
+            data_version: 1,
+            metadata: CompoundTag::new(),
+            width: 0,
+            height: 0,
+            length: 0,
+            offset: [0, 0, 0],
+            palette_max: 1,
+            palette: vec![("minecraft:chest".to_owned(), 1)].into_iter().collect(),
+            block_data: vec![1],
+            block_entities: vec![],
+            entities: None,
+        };
+
+        assert_eq!(has_invalid_nbt(schem), true);
+    }
+
+    #[test]
+    fn test_has_invalid_nbt_2() {
+        let schem = SpongeSchematic {
+            data_version: 1,
+            metadata: CompoundTag::new(),
+            width: 1,
+            height: 1,
+            length: 1,
+            offset: [0, 0, 0],
+            palette_max: 1,
+            palette: vec![("minecraft:chest".to_owned(), 1)].into_iter().collect(),
+            block_data: vec![1],
+            block_entities: vec![
+                BlockEntity {
+                    id: "minecraft:chest".to_owned(),
+                    pos: [0, 0, 0],
+                }
+            ],
+            entities: None,
+        };
+
+        assert_eq!(has_invalid_nbt(schem), false);
+    }
+
+    #[test]
+    fn test_has_invalid_nbt_3() {
+        let schem = SpongeSchematic {
+            data_version: 1,
+            metadata: CompoundTag::new(),
+            width: 2,
+            height: 1,
+            length: 1,
+            offset: [0, 0, 0],
+            palette_max: 1,
+            palette: vec![("minecraft:chest".to_owned(), 1), ("minecraft:stone".to_owned(), 2)].into_iter().collect(),
+            block_data: vec![1, 2],
+            block_entities: vec![
+                BlockEntity {
+                    id: "minecraft:chest".to_owned(),
+                    pos: [1, 0, 0],
+                }
+            ],
+            entities: None,
+        };
+
+        assert_eq!(has_invalid_nbt(schem), true);
+    }
 }
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