Millihertz quasi-periodic oscillations reported in three neutron-star low mass X-ray binaries have been suggested to be a mode of marginally stable nuclear burning on the neutron star surface . In this Letter , we show that close to the transition between the island and the banana state , 4U 1636–53 shows mHz QPOs whose frequency systematically decreases with time until the oscillations disappear and a Type I X-ray burst occurs . There is a strong correlation between the QPO frequency \nu and the occurrence of X-ray bursts : when \nu \gtrsim 9 mHz no bursts occur , while \nu \lesssim 9 mHz does allow the occurrence of bursts . The mHz QPO frequency constitutes the first identified observable that can be used to predict the occurrence of X-ray bursts . If a systematic frequency drift occurs , then a burst happens within a few kilo-seconds after \nu drops below 9 mHz . This observational result confirms that the mHz QPO phenomenon is intimately related with the processes that lead to a thermonuclear burst .