diff --git a/types/heartbeat_test.go b/types/heartbeat_test.go
index 8a0967128..660ccd0f9 100644
--- a/types/heartbeat_test.go
+++ b/types/heartbeat_test.go
@@ -40,17 +40,17 @@ func TestHeartbeatWriteSignBytes(t *testing.T) {
 
 	hb := &Heartbeat{ValidatorIndex: 1, Height: 10, Round: 1}
 	hb.WriteSignBytes("0xdeadbeef", buf, &n, &err)
-	require.Equal(t, string(buf.Bytes()), `{"chain_id":"0xdeadbeef","heartbeat":{"height":10,"round":1,"sequence":0,"validator_address":"","validator_index":1}}`)
+	require.Equal(t, buf.String(), `{"chain_id":"0xdeadbeef","heartbeat":{"height":10,"round":1,"sequence":0,"validator_address":"","validator_index":1}}`)
 
 	buf.Reset()
 	plainHb := &Heartbeat{}
 	plainHb.WriteSignBytes("0xdeadbeef", buf, &n, &err)
-	require.Equal(t, string(buf.Bytes()), `{"chain_id":"0xdeadbeef","heartbeat":{"height":0,"round":0,"sequence":0,"validator_address":"","validator_index":0}}`)
+	require.Equal(t, buf.String(), `{"chain_id":"0xdeadbeef","heartbeat":{"height":0,"round":0,"sequence":0,"validator_address":"","validator_index":0}}`)
 
 	require.Panics(t, func() {
 		buf.Reset()
 		var nilHb *Heartbeat
 		nilHb.WriteSignBytes("0xdeadbeef", buf, &n, &err)
-		require.Equal(t, string(buf.Bytes()), "null")
+		require.Equal(t, buf.String(), "null")
 	})
 }