diff --git a/test_libs/pyspec/eth2spec/test/helpers/custody.py b/test_libs/pyspec/eth2spec/test/helpers/custody.py
index 681add457..bc70c9fa8 100644
--- a/test_libs/pyspec/eth2spec/test/helpers/custody.py
+++ b/test_libs/pyspec/eth2spec/test/helpers/custody.py
@@ -27,7 +27,7 @@ def get_valid_early_derived_secret_reveal(spec, state, epoch=None):
             domain_type=spec.DOMAIN_RANDAO,
             message_epoch=epoch,
         ),
-    )
+    )[:32]  # TODO(Carl): mask is 32 bytes, and signature is 96? Correct to slice the first 32 out?
 
     return spec.EarlyDerivedSecretReveal(
         revealed_index=revealed_index,