diff --git a/executorlib/interactive/flux.py b/executorlib/interactive/flux.py
index 6537bbef..2c324828 100644
--- a/executorlib/interactive/flux.py
+++ b/executorlib/interactive/flux.py
@@ -7,7 +7,7 @@
 from executorlib.standalone.interactive.spawner import BaseSpawner
 
 
-def validate_max_workers(max_workers, cores, threads_per_core):
+def validate_max_workers(max_workers: int, cores: int, threads_per_core: int):
     handle = flux.Flux()
     cores_total = flux.resource.list.resource_list(handle).get().up.ncores
     cores_requested = max_workers * cores * threads_per_core
diff --git a/executorlib/interactive/slurm.py b/executorlib/interactive/slurm.py
index b662061a..8c962529 100644
--- a/executorlib/interactive/slurm.py
+++ b/executorlib/interactive/slurm.py
@@ -6,8 +6,8 @@
 SLURM_COMMAND = "srun"
 
 
-def validate_max_workers(max_workers, cores, threads_per_core):
-    cores_total = os.environ["SLURM_NTASKS"] * os.environ["SLURM_CPUS_PER_TASK"]
+def validate_max_workers(max_workers: int, cores: int, threads_per_core: int):
+    cores_total = int(os.environ["SLURM_NTASKS"]) * int(os.environ["SLURM_CPUS_PER_TASK"])
     cores_requested = max_workers * cores * threads_per_core
     if cores_total < cores_requested:
         raise ValueError(