diff --git a/tunix/rl/utils.py b/tunix/rl/utils.py
index 6b54c62bc..b6599ec77 100644
--- a/tunix/rl/utils.py
+++ b/tunix/rl/utils.py
@@ -34,8 +34,11 @@
 
 def is_positive_integer(value: int | None, name: str):
   """Checks if the value is positive."""
-  if value is not None and (not value.is_integer() or value <= 0):
-    raise ValueError(f"{name} must be a positive integer. Got: {value}")
+  if value is not None:
+    if not isinstance(value, int):
+      raise ValueError(f"{name} must be an integer. Got type: {type(value)}")
+    if value <= 0:
+      raise ValueError(f"{name} must be a positive integer. Got: {value}")
 
 
 def check_divisibility(