diff --git a/beacon_chain/spec/crypto.nim b/beacon_chain/spec/crypto.nim
index 0f321a708..fbd8830f0 100644
--- a/beacon_chain/spec/crypto.nim
+++ b/beacon_chain/spec/crypto.nim
@@ -328,7 +328,15 @@ proc readValue*(reader: var JsonReader, value: var Signature) {.inline.} =
 template fromSszBytes*(T: type BlsValue, bytes: openarray[byte]): auto =
   fromBytes(T, bytes)
 
+# Initialization
+# ----------------------------------------------------------------------
+
 # For confutils
 func init*(T: typedesc[ValidatorPrivKey], hex: string): T {.inline.} =
   let success = result.fromHex(hex)
   doAssert success, "Private key is invalid" # Don't display private keys even if invalid
+
+# For mainchain monitor
+func init*(T: typedesc[ValidatorPubKey], data: array[48, byte]): T {.inline.} =
+  let success = result.fromBytes(data)
+  doAssert success, "Public key is invalid" # Don't display private keys even if invalid