diff --git a/pytorch_lightning/models/trainer.py b/pytorch_lightning/models/trainer.py
index 91de1b69..ba5e7272 100644
--- a/pytorch_lightning/models/trainer.py
+++ b/pytorch_lightning/models/trainer.py
@@ -393,9 +393,9 @@ 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
             try:
                 nb_slurm_tasks = int(os.environ['SLURM_NTASKS'])
-                nb_requested_gpus = len(self.data_parallel_device_ids) * self.nb_gpu_nodes
                 is_slurm_managing_tasks = nb_slurm_tasks == nb_requested_gpus
             except Exception as e:
                 # likely not on slurm, so set the slurm managed flag to false