It is not exactly the tone of a man who has just been told some economic news rather better than many expected.
"We must not be complacent," the Chancellor of the Exchequer said in response to borrowing figures that were the rosiest in 18 years.
Philip Hammond knows that what borrowing figures can give, they can also take away.
Receipts from taxes on our salaries and taxes on what we buy (VAT) are higher - but if there were a downturn in the economy, that could go into reverse.
Spending by government departments is sluggish - but it is still early in the financial year and the figures are volatile.
Payments to the European Union are lower - but that is about the timing of the bills rather than any change in annual costs.
And the boost from government asset sales (such as the sale of part of the stake in Royal Bank of Scotland) will not be repeated every month.
The Treasury is trying to keep a lid on expectations ahead of the Budget in November.
If there is more "wriggle room" in the public finances because the government is borrowing less, that has to be seen in context, government sources argue.
Plenty of spending pledges have already been made.
Theresa May has promised substantial new funding for the NHS, suggesting that taxes may have to rise to pay for it.
The government has also agreed to higher public sector pay settlements.
And there are plenty of other demands for new money already nestling in the Treasury's in-tray.
Arguments for increased spending on the prison service, the police, defence and social care are all being made.
Demands the Treasury is at present resisting.
With the total debt - that is all the money the government has borrowed over many years - at £1.8 trillion, the Treasury says there is still work to do "repairing" the public finances.
Public finances which Labour says are still in a shocking state.
Today's borrowing figures are better news.
Mr Hammond remains cautious, though, in case that better news - with much uncertainty ahead - does not last.