diff --git a/trie-db/test/src/triedb.rs b/trie-db/test/src/triedb.rs
index 92fbe820..04e0f710 100644
--- a/trie-db/test/src/triedb.rs
+++ b/trie-db/test/src/triedb.rs
@@ -107,8 +107,8 @@ fn iterator_internal<T: TrieLayout>() {
 
 test_layouts!(iterator_seek, iterator_seek_internal);
 fn iterator_seek_internal<T: TrieLayout>() {
-	let d = vec![b"A".to_vec(), b"AA".to_vec(), b"AB".to_vec(), b"B".to_vec()];
-	let vals = vec![vec![0; 32], vec![1; 32], vec![2; 32], vec![3; 32]];
+	let d = vec![b"A".to_vec(), b"AA".to_vec(), b"AB".to_vec(), b"AS".to_vec(), b"B".to_vec()];
+	let vals = vec![vec![0; 32], vec![1; 32], vec![2; 32], vec![4; 32], vec![3; 32]];
 
 	let mut memdb = PrefixedMemoryDB::<T>::default();
 	let mut root = Default::default();
@@ -133,11 +133,15 @@ fn iterator_seek_internal<T: TrieLayout>() {
 	let iter = trie_db::TrieDBIterator::new_prefixed(&t, b"aaaaa").unwrap();
 	assert_eq!(&vals[..0], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
 	let iter = trie_db::TrieDBIterator::new_prefixed(&t, b"A").unwrap();
-	assert_eq!(&vals[..3], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
+	assert_eq!(&vals[..4], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
 	let iter = trie_db::TrieDBIterator::new_prefixed_then_seek(&t, b"A", b"AA").unwrap();
-	assert_eq!(&vals[1..3], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
+	assert_eq!(&vals[1..4], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
+	let iter = trie_db::TrieDBIterator::new_prefixed_then_seek(&t, b"A", b"AR").unwrap();
+	assert_eq!(&vals[3..4], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
+	let iter = trie_db::TrieDBIterator::new_prefixed_then_seek(&t, b"A", b"AS").unwrap();
+	assert_eq!(&vals[3..4], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
 	let iter = trie_db::TrieDBIterator::new_prefixed_then_seek(&t, b"A", b"AB").unwrap();
-	assert_eq!(&vals[2..3], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
+	assert_eq!(&vals[2..4], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
 	let iter = trie_db::TrieDBIterator::new_prefixed_then_seek(&t, b"", b"AB").unwrap();
 	assert_eq!(&vals[2..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
 	let mut iter = t.iter().unwrap();
@@ -151,10 +155,10 @@ fn iterator_seek_internal<T: TrieLayout>() {
 	assert_eq!(&vals[3..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
 	let mut iter = t.iter().unwrap();
 	iter.seek(b"B").unwrap();
-	assert_eq!(&vals[3..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
+	assert_eq!(&vals[4..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
 	let mut iter = t.iter().unwrap();
 	iter.seek(b"C").unwrap();
-	assert_eq!(&vals[4..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
+	assert_eq!(&vals[5..], &iter.map(|x| x.unwrap().1).collect::<Vec<_>>()[..]);
 }
 
 test_layouts!(get_length_with_extension, get_length_with_extension_internal);