Negative feedback is a conserved element in the maintenance of circadian rhythms. In Neurospora crassa, rhythmic oscillation is under the control of a central system in which the White Collar transcription-factor complex (WCC) stimulates expression of the clock protein FREQUENCY (FRQ). FRQ associates with the FRQ-interacting RNA helicase (FRH), and together they recruit factors that inactivate the WCC and subsequently promote the destruction of FRQ, thus resetting the cycle. Although FRH was known to stabilize FRQ and to stimulate the interaction between FRQ and the WCC, the molecular basis for FRH's activity in regulating periodicity remained poorly characterized. Dunlap and colleagues now expose an unexpected mechanism of action for FRH that is independent of its enzymatic activity and sheds light on the hitherto-underappreciated characteristics of FRQ as an intrinsically disordered protein (IDP). First, the authors demonstrated that although the helicase activity of FRH is required for normal growth, the clock function of FRH could be fully restored by a mutant devoid of helicase activity. They then showed that FRH exhibits many of the biochemical characteristics of an IDP and that its clock function probably lies in its ability to act as a 'nanny' protein to protect FRQ from premature degradation and/or spurious interactions. Although it is yet to be determined whether similar interactions are involved in regulating other circadian oscillators, the findings highlight the emerging concept that the functional properties of IDPs might often be in stabilizing interactions with cellular factors that carry distinct cellular roles. (Mol. Cell doi:10.1016/j.molcel.2013.11.005, 5 December 2013)