diff --git a/sharding/shard.go b/sharding/shard.go
index 816ca2c84..fb38cc829 100644
--- a/sharding/shard.go
+++ b/sharding/shard.go
@@ -52,7 +52,7 @@ func (s *Shard) HeaderByHash(hash *common.Hash) (*CollationHeader, error) {
 		return nil, fmt.Errorf("get failed: %v", err)
 	}
 	if encoded == nil {
-		return nil, fmt.Errorf("no value set for header hash: %v", hash.String())
+		return nil, fmt.Errorf("no value set for header hash: %vs", hash.Hex())
 	}
 
 	var header CollationHeader
@@ -158,10 +158,7 @@ func (s *Shard) SetAvailability(chunkRoot *common.Hash, availability bool) error
 	} else {
 		encoded = []byte{0}
 	}
-	if err := s.shardDB.Put(key, encoded); err != nil {
-		return err
-	}
-	return nil
+	return s.shardDB.Put(key, encoded)
 }
 
 // SaveHeader adds the collation header to shardDB.
@@ -177,10 +174,7 @@ func (s *Shard) SaveHeader(header *CollationHeader) error {
 	}
 
 	// uses the hash of the header as the key.
-	if err := s.shardDB.Put(header.Hash(), encoded); err != nil {
-		return fmt.Errorf("cannot update shardDB: %v", err)
-	}
-	return nil
+	return s.shardDB.Put(header.Hash(), encoded)
 }
 
 // SaveBody adds the collation body to the shardDB and sets availability.
@@ -245,7 +239,7 @@ func (s *Shard) SetCanonical(header *CollationHeader) error {
 // dataAvailabilityLookupKey formats a string that will become a lookup
 // key in the shardDB.
 func dataAvailabilityLookupKey(chunkRoot *common.Hash) common.Hash {
-	key := fmt.Sprintf("availability-lookup:%s", chunkRoot.String())
+	key := fmt.Sprintf("availability-lookup:%s", chunkRoot.Hex())
 	return common.BytesToHash([]byte(key))
 }
 
diff --git a/sharding/shard_test.go b/sharding/shard_test.go
index 4c174a200..cd3d90af5 100644
--- a/sharding/shard_test.go
+++ b/sharding/shard_test.go
@@ -191,8 +191,8 @@ func TestShard_CanonicalHeaderHash(t *testing.T) {
 		t.Errorf("should throw error if a non-existent period, shardID pair is used")
 	}
 
-	if canonicalHeaderHash.String() != headerHash.String() {
-		t.Errorf("header hashes do not match. want=%s. got=%s", headerHash.String(), canonicalHeaderHash.String())
+	if canonicalHeaderHash.Hex() != headerHash.Hex() {
+		t.Errorf("header hashes do not match. want=%s. got=%s", headerHash.Hex(), canonicalHeaderHash.Hex())
 	}
 }
 
@@ -337,7 +337,7 @@ func TestShard_CheckAvailability(t *testing.T) {
 		t.Errorf("could not check availability: %v", err)
 	}
 	if !available {
-		t.Errorf("collation body is not available: chunkRoot=%v, body=%v", header.ChunkRoot(), collation.body)
+		t.Errorf("collation body is not available: chunkRoot=%s, body=%v", header.ChunkRoot().Hex(), collation.body)
 	}
 }