diff --git a/pkg/btree/bptree.go b/pkg/btree/bptree.go
index 5c9fa57c..030f9048 100644
--- a/pkg/btree/bptree.go
+++ b/pkg/btree/bptree.go
@@ -239,6 +239,13 @@ func (t *BPTree) traverse(key ReferencedValue, node *BPTreeNode, ptr MemoryPoint
 }
 
 func (t *BPTree) Insert(key ReferencedValue, value MemoryPointer) error {
+
+	if t.Width != uint16(0) {
+		if uint16(len(key.Value)) != t.Width-1 {
+			return fmt.Errorf("key to insert does not match with bptree width. Expected width: %v, got: %v", t.Width, len(key.Value))
+		}
+	}
+
 	root, rootOffset, err := t.root()
 	if err != nil {
 		return fmt.Errorf("read root node: %w", err)
@@ -268,7 +275,8 @@ func (t *BPTree) Insert(key ReferencedValue, value MemoryPointer) error {
 	n := path[0].node
 	j, found := slices.BinarySearchFunc(n.Keys, key, CompareReferencedValues)
 	if found {
-		return fmt.Errorf("key already exists")
+
+		return fmt.Errorf("key already exists. Data pointer: %v", key.DataPointer)
 	}
 	if j == len(n.Keys) {
 		n.Keys = append(n.Keys, key)
diff --git a/pkg/btree/bptree_test.go b/pkg/btree/bptree_test.go
index 8dffba6a..51376666 100644
--- a/pkg/btree/bptree_test.go
+++ b/pkg/btree/bptree_test.go
@@ -569,6 +569,35 @@ func TestBPTree_Iteration_FirstLast(t *testing.T) {
 	})
 }
 
+func TestBPTree_IncorrectWidth(t *testing.T) {
+
+	t.Run("float tree", func(t *testing.T) {
+		b := buftest.NewSeekableBuffer()
+		p, err := pagefile.NewPageFile(b)
+		if err != nil {
+			t.Fatal(err)
+		}
+		floatTree := &BPTree{PageFile: p, MetaPage: newTestMetaPage(t, p), Width: uint16(9)}
+
+		if err := floatTree.Insert(ReferencedValue{Value: []byte{1}, DataPointer: MemoryPointer{Offset: uint64(0)}}, MemoryPointer{Offset: uint64(0), Length: uint32(39)}); err == nil {
+			t.Fatalf("should error %v", err)
+		}
+	})
+
+	t.Run("nil tree", func(t *testing.T) {
+		b := buftest.NewSeekableBuffer()
+		p, err := pagefile.NewPageFile(b)
+		if err != nil {
+			t.Fatal(err)
+		}
+		nilTree := &BPTree{PageFile: p, MetaPage: newTestMetaPage(t, p), Width: uint16(1)}
+
+		if err := nilTree.Insert(ReferencedValue{Value: []byte{1}, DataPointer: MemoryPointer{Offset: uint64(0)}}, MemoryPointer{Offset: uint64(0), Length: uint32(39)}); err == nil {
+			t.Fatalf("should error %v", err)
+		}
+	})
+}
+
 func TestBPTree_Iteration_Overcount(t *testing.T) {
 	b := buftest.NewSeekableBuffer()
 	p, err := pagefile.NewPageFile(b)
@@ -588,7 +617,7 @@ func TestBPTree_Iteration_Overcount(t *testing.T) {
 		}
 	}
 
-	t.Run("finds exactly 10 occurences of 23", func(t *testing.T) {
+	t.Run("finds exactly 10 occurrences of 23", func(t *testing.T) {
 		buf := make([]byte, 8)
 		binary.BigEndian.PutUint64(buf, math.Float64bits(23))