diff --git a/Blockchain/Sources/Blockchain/Types/AvailabilitySpecifications.swift b/Blockchain/Sources/Blockchain/Types/AvailabilitySpecifications.swift
index 4a8f0346..6187a37d 100644
--- a/Blockchain/Sources/Blockchain/Types/AvailabilitySpecifications.swift
+++ b/Blockchain/Sources/Blockchain/Types/AvailabilitySpecifications.swift
@@ -15,7 +15,7 @@ public struct AvailabilitySpecifications: Sendable, Equatable, Codable {
     public var segmentRoot: Data32
 
     // n
-    public var segmentCount: Int
+    public var segmentCount: UInt16
 
     public init(
         workPackageHash: Data32,
diff --git a/JAMTests/Tests/JAMTests/CodecTests.swift b/JAMTests/Tests/JAMTests/CodecTests.swift
index f5787dc1..a509dff7 100644
--- a/JAMTests/Tests/JAMTests/CodecTests.swift
+++ b/JAMTests/Tests/JAMTests/CodecTests.swift
@@ -178,6 +178,7 @@ struct CodecTests {
                 "len": json["length"]!,
                 "erasure_root": json["erasureRoot"]!,
                 "exports_root": json["segmentRoot"]!,
+                "exports_count": json["segmentCount"]!,
             ].json
         }
         if let value = value as? ExtrinsicGuarantees {