diff --git a/Blockchain/Sources/Blockchain/Runtime.swift b/Blockchain/Sources/Blockchain/Runtime.swift
index ded76a5f..537370da 100644
--- a/Blockchain/Sources/Blockchain/Runtime.swift
+++ b/Blockchain/Sources/Blockchain/Runtime.swift
@@ -129,8 +129,8 @@ public final class Runtime {
         item.blocks += 1
         item.tickets += UInt32(block.extrinsic.tickets.tickets.count)
         item.preimages += UInt32(block.extrinsic.preimages.preimages.count)
-        // try to  change  preimage size to preimage data or serviceIndices
-        item.preimagesBytes += UInt32(block.extrinsic.preimages.preimages.count*ConstInt32.value)
+        // try to  change  preimage size to serviceIndices
+        item.preimagesBytes += UInt32(block.extrinsic.preimages.preimages.reduce(into: 0) { $0 += $1.serviceIndices })
         acc[block.header.authorIndex] = item
 
         for report in block.extrinsic.reports.guarantees {
diff --git a/Blockchain/Sources/Blockchain/Types/ExtrinsicPreimages.swift b/Blockchain/Sources/Blockchain/Types/ExtrinsicPreimages.swift
index 311bef0d..c7cd5a3f 100644
--- a/Blockchain/Sources/Blockchain/Types/ExtrinsicPreimages.swift
+++ b/Blockchain/Sources/Blockchain/Types/ExtrinsicPreimages.swift
@@ -4,10 +4,10 @@ import Utils
 
 public struct ExtrinsicPreimages: Sendable, Equatable {
     public struct SizeAndData: Sendable, Equatable {
-        public var serviceIndices: ServiceIdentifier
+        public var serviceIndices: ServiceIndices
         public var data: Data
 
-        public init(serviceIndices: ServiceIdentifier, data: Data) {
+        public init(serviceIndices: ServiceIndices, data: Data) {
             self.serviceIndices = serviceIndices
             self.data = data
         }
diff --git a/Blockchain/Sources/Blockchain/Types/primitives.swift b/Blockchain/Sources/Blockchain/Types/primitives.swift
index 4f81431c..6880a6da 100644
--- a/Blockchain/Sources/Blockchain/Types/primitives.swift
+++ b/Blockchain/Sources/Blockchain/Types/primitives.swift
@@ -4,7 +4,9 @@ public typealias Balances = UInt64
 public typealias ServiceIdentifier = Data32
 public typealias TimeslotIndex = UInt32
 public typealias Gas = UInt64
+public typealias ServiceIndices = UInt32
 public typealias DataLength = UInt32
+
 public typealias ValidatorIndex = UInt32 // TODO: confirm this
 public typealias CoreIndex = UInt32 // TODO: confirm this
 public typealias TicketIndex = UInt8