We prove a variation of Gronwall’s lemma. The formulation and proof of the classical Gronwall’s lemma can be found in [1]. We prove here a variation of this lemma, which we were not able to find in the literature. Lemma 1 Let g : [0,∞[→ R be a continuous function, λ > 0 and C ≥ 0. Assume that ∀u, t 0 ≤ u ≤ t g(t)− g(u) ≤ − ∫ t