diff --git a/beacon_chain/spec/state_transition_epoch.nim b/beacon_chain/spec/state_transition_epoch.nim
index b80601fdb..a0b96c033 100644
--- a/beacon_chain/spec/state_transition_epoch.nim
+++ b/beacon_chain/spec/state_transition_epoch.nim
@@ -148,9 +148,9 @@ proc process_justification_and_finalization*(
   ## matter -- in the next epoch, they'll be 2 epochs old, when BeaconState
   ## tracks current_epoch_attestations and previous_epoch_attestations only
   ## per
-  ## https://github.com/ethereum/eth2.0-specs/blob/v0.10.1/specs/phase0/beacon-chain.md#attestations
+  ## https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/beacon-chain.md#attestations
   ## and `get_matching_source_attestations(...)` via
-  ## https://github.com/ethereum/eth2.0-specs/blob/v0.10.1/specs/phase0/beacon-chain.md#helper-functions-1
+  ## https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/beacon-chain.md#helper-functions-1
   ## and
   ## https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/specs/phase0/beacon-chain.md#final-updates
   ## after which the state.previous_epoch_attestations is replaced.
diff --git a/beacon_chain/ssz/bytes_reader.nim b/beacon_chain/ssz/bytes_reader.nim
index 96a5b8df0..e0cd0ea81 100644
--- a/beacon_chain/ssz/bytes_reader.nim
+++ b/beacon_chain/ssz/bytes_reader.nim
@@ -58,6 +58,14 @@ template fromSszBytes*(T: type BitSeq, bytes: openarray[byte]): auto =
   BitSeq @bytes
 
 func fromSszBytes*[N](T: type BitList[N], bytes: openarray[byte]): auto {.raisesssz.} =
+  if bytes.len == 0:
+    # https://github.com/ethereum/eth2.0-specs/blob/v0.11.1/ssz/simple-serialize.md#bitlistn
+    # "An additional 1 bit is added to the end, at index e where e is the
+    # length of the bitlist (not the limit), so that the length in bits will
+    # also be known."
+    # It's not possible to have a literally 0-byte (raw) Bitlist.
+    # https://github.com/status-im/nim-beacon-chain/issues/931
+    raise newException(MalformedSszError, "SSZ input Bitlist too small")
   BitList[N] @bytes
 
 func fromSszBytes*[N](T: type BitArray[N], bytes: openarray[byte]): T {.raisesssz.} =
diff --git a/tests/test_mainchain_monitor.nim b/tests/test_mainchain_monitor.nim
index 6ad86be49..1ba6ba50d 100644
--- a/tests/test_mainchain_monitor.nim
+++ b/tests/test_mainchain_monitor.nim
@@ -1,3 +1,5 @@
+{.used.}
+
 import
   unittest,
   chronos, web3/ethtypes,