diff --git a/pytorch_lightning/models/trainer.py b/pytorch_lightning/models/trainer.py
index ba5e7272..79d2c2dc 100644
--- a/pytorch_lightning/models/trainer.py
+++ b/pytorch_lightning/models/trainer.py
@@ -394,6 +394,7 @@ class Trainer(TrainerIO):
             # whenever we have the correct number of tasks, we let slurm manage processes
             # otherwise we launch the required number of processes
             nb_requested_gpus = len(self.data_parallel_device_ids) * self.nb_gpu_nodes
+            nb_slurm_tasks = 0
             try:
                 nb_slurm_tasks = int(os.environ['SLURM_NTASKS'])
                 is_slurm_managing_tasks = nb_slurm_tasks == nb_requested_gpus