diff --git a/Blockchain/Sources/Blockchain/Blockchain.swift b/Blockchain/Sources/Blockchain/Blockchain.swift
index f0ff385d..2a28dcba 100644
--- a/Blockchain/Sources/Blockchain/Blockchain.swift
+++ b/Blockchain/Sources/Blockchain/Blockchain.swift
@@ -34,7 +34,7 @@ public class Blockchain {
     }
 
     private func addState(_ state: StateRef) {
-        stateByBlockHash[state.value.lastBlock.header.hash] = state
+        stateByBlockHash[state.value.lastBlock.header.hash()] = state
         stateByTimeslot[state.value.lastBlock.header.timeslotIndex, default: []].append(state)
     }
 }
diff --git a/Blockchain/Sources/Blockchain/Types/Header.swift b/Blockchain/Sources/Blockchain/Types/Header.swift
index e6577ac7..49ae07e3 100644
--- a/Blockchain/Sources/Blockchain/Types/Header.swift
+++ b/Blockchain/Sources/Blockchain/Types/Header.swift
@@ -119,7 +119,11 @@ extension Header: ScaleCodec.Encodable {
 }
 
 extension Header {
-    public func hash() throws -> Data32 {
-        try blake2b256(ScaleCodec.encode(self))
+    public func hash() -> Data32 {
+        do {
+            return try blake2b256(ScaleCodec.encode(self))
+        } catch let e {
+            fatalError("Failed to hash header: \(e)")
+        }
     }
 }