Shares of Canadian marijuana producer Aurora Cannabis were 5% higher midday Tuesday after it reported a sharp swing to profitability and said it is planning a U.S. listing. But a closer look at its results suggests reasons for caution.

Marijuana will become legal for recreational use next month in Canada. This means big opportunities for companies like Aurora, which already is growing quickly. Revenue more than tripled from a year earlier in its most recent fiscal quarter.

Aurora also posted a net profit of C$79.27 million ($61.3 million) in the quarter, compared with a loss of C$4.82 million in the year-ago period. But this is where things get hazy: The swing was primarily due to noncash, unrealized gains on derivatives and marketable securities. Aurora holds minority stakes in several other marijuana-related companies, including Choom Holdings and The Green Organic Dutchman, whose shares have also soared.

At a stratospheric 298 times sales, according to FactSet, prudent investors shouldn’t consider inhaling.