diff --git a/slot_diff_attest.py b/slot_diff_attest.py
index 98e6a58..252f082 100644
--- a/slot_diff_attest.py
+++ b/slot_diff_attest.py
@@ -140,9 +140,14 @@ def main() -> None:
     chain_id = w3.eth.chain_id
     tip = w3.eth.block_number
     print(f"🌐 Connected chainId={chain_id}, tip={tip}")
-    if block_a > tip or block_b > tip: print(f"⚠️ Requested block beyond tip {tip}; clamping upper bound."); block_b = min(block_b, tip)
+       if block_a > tip or block_b > tip:
+        print(f"⚠️ Requested block beyond tip {tip}; clamping upper bound.", file=sys.stderr)
+        block_b = min(block_b, tip)
+
     if block_b > tip:
-        print(f"⚠️ block_b {block_b} > tip {tip}; clamping."); block_b = tip
+        print(f"⚠️ block_b {block_b} > tip {tip}; clamping.", file=sys.stderr)
+        block_b = tip
+
     if not w3.eth.get_code(address):
         print("⚠️ Target has no contract code — likely an EOA (reads will be zero).")
      if not code: print("❌ Target has no contract code (EOA)."); sys.exit(2)