diff --git a/GPRL/utils/gp_utils.py b/GPRL/utils/gp_utils.py
index 1541984d9ebb3e592e6454c3edaacd1e85c2c16d..6deedfca7f6f02da838fdd100f7ecc2841e32908 100644
--- a/GPRL/utils/gp_utils.py
+++ b/GPRL/utils/gp_utils.py
@@ -67,7 +67,7 @@ def mutate(individual, expr=None, pset=None, mode="one", mu=0, std=1):#mutate th
         return gp.mutUniform(individual, expr=expr, pset=pset)
 
 def selQDRandom(grid, k, cellSelection=random.choice):
-    idxs = [k for k, v in grid._solutions.items() if v]
+    idxs = [key for key, v in grid._solutions.items() if v]
     return [cellSelection(grid._solutions[random.choice(idxs)]) for _ in range(k)]
 
 def selFitProp(individuals, fit_attr="fitness"):#cell fitness proportionnal selection