diff --git a/specs/altair/beacon-chain.md b/specs/altair/beacon-chain.md
index 1ce78ad7c..998958643 100644
--- a/specs/altair/beacon-chain.md
+++ b/specs/altair/beacon-chain.md
@@ -461,7 +461,7 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
 
     # Participation flag indices
     participation_flag_indices = []
-    if is_matching_head and is_matching_target and state.slot <= data.slot + MIN_ATTESTATION_INCLUSION_DELAY:
+    if is_matching_head and is_matching_target and state.slot == data.slot + MIN_ATTESTATION_INCLUSION_DELAY:
         participation_flag_indices.append(TIMELY_HEAD_FLAG_INDEX)
     if is_matching_source and state.slot <= data.slot + integer_squareroot(SLOTS_PER_EPOCH):
         participation_flag_indices.append(TIMELY_SOURCE_FLAG_INDEX)