diff --git a/ouroboros-consensus-byron/test/Test/ThreadNet/DualPBFT.hs b/ouroboros-consensus-byron/test/Test/ThreadNet/DualPBFT.hs
index c4482ca3507..ccce9ff2553 100644
--- a/ouroboros-consensus-byron/test/Test/ThreadNet/DualPBFT.hs
+++ b/ouroboros-consensus-byron/test/Test/ThreadNet/DualPBFT.hs
@@ -96,6 +96,11 @@ prop_convergence setup = withMaxSuccess 10 $
     -- The test infrastructure allows nodes to forge in slot 0; however, the
     -- cardano-ledger-specs code causes @PBFTFailure (SlotNotAfterLastBlock
     -- (Slot 0) (Slot 0))@ in that case. So we discard such tests.
+    --
+    -- This is ultimately due to the spec not modeling EBBs, while Byron always
+    -- requires that success of the genesis block is always the epoch 0 EBB. As
+    -- a result, the PBFT implementation tests the slot progression with @<=@
+    -- to accomodate EBBs whereas the executable STS spec uses @<@.
     mightForgeInSlot0 :: Bool
     mightForgeInSlot0 = case refResult of
       Ref.Forked _ m        -> any (0 `Set.member`) m