diff --git a/tasks/common.py b/tasks/common.py
index dcd2e91..f2228eb 100644
--- a/tasks/common.py
+++ b/tasks/common.py
@@ -6,6 +6,9 @@ Example tasks: MMLU, ARC-Easy, ARC-Challenge, GSM8K, HumanEval, SmolTalk.
 """
 
 import random
+import logging
+
+logger = logging.getLogger(__name__)
 
 class Task:
     """
@@ -34,7 +37,15 @@ class Task:
 
     def __len__(self):
         start = self.start
-        stop = self.num_examples() if self.stop is None else self.stop
+        num_ex = self.num_examples()
+        if self.stop is not None and self.stop > num_ex:
+            # Warn once, then cap stop
+            logger.warning(
+                f"Stop parameter ({self.stop}) exceeds dataset size ({num_ex}). "
+                f"Using {num_ex} examples instead."
+            )
+            self.stop = num_ex
+        stop = num_ex if self.stop is None else self.stop
         step = self.step
         span = stop - start
         num = (span + step - 1) // step # ceil_div(span, step)