diff --git a/Sources/GISTools/Extensions/FeatureIdentifierExtensions.swift b/Sources/GISTools/Extensions/FeatureIdentifierExtensions.swift
new file mode 100644
index 0000000..4bf5a14
--- /dev/null
+++ b/Sources/GISTools/Extensions/FeatureIdentifierExtensions.swift
@@ -0,0 +1,23 @@
+import Foundation
+
+// MARK: Public
+
+extension Feature.Identifier {
+
+    public var int64Value: Int64? {
+        switch self {
+        case .int(let int): Int64(exactly: int)
+        case .uint(let uint): Int64(exactly: uint)
+        default: nil
+        }
+    }
+
+    public var uint64Value: UInt64? {
+        switch self {
+        case .int(let int): UInt64(exactly: int)
+        case .uint(let uint): UInt64(exactly: uint)
+        default: nil
+        }
+    }
+
+}
diff --git a/Sources/GISTools/GeoJson/Feature.swift b/Sources/GISTools/GeoJson/Feature.swift
index f9f1f5c..cf71cb3 100644
--- a/Sources/GISTools/GeoJson/Feature.swift
+++ b/Sources/GISTools/GeoJson/Feature.swift
@@ -5,39 +5,67 @@ public struct Feature: GeoJson {
 
     /// A GeoJSON identifier that can either be a string or number.
     public enum Identifier: Equatable, Hashable, CustomStringConvertible, Sendable {
+
+#if _pointerBitWidth(_32)
+        public typealias IntId = Int64
+        public typealias UIntId = UInt64
+#else
+        public typealias IntId = Int
+        public typealias UIntId = UInt
+#endif
+
         case string(String)
-        case int(Int)
+        case int(IntId)
+        case uint(UIntId)
         case double(Double)
 
         public init?(value: Any?) {
             guard let value else { return nil }
-            if let int = value as? Int {
+
+            switch value {
+            case let int as IntId:
                 self = .int(int)
-            }
-            else if let string = value as? String {
+
+            case let uint as UIntId:
+                self = .uint(uint)
+
+            case let string as String:
                 self = .string(string)
-            }
-            else if let double = value as? Double {
+
+            case let double as Double:
                 self = .double(double)
-            }
-            else {
+
+            case let binaryInt as (any BinaryInteger):
+                if let int = IntId(exactly: binaryInt) {
+                    self = .int(int)
+                }
+                else if let uint = UIntId(exactly: binaryInt) {
+                    self = .uint(uint)
+                }
+                else {
+                    return nil
+                }
+
+            default:
                 return nil
             }
         }
 
         public var asJson: Any {
             switch self {
-            case .double(let double): return double
-            case .int(let int): return int
-            case .string(let string): return string
+            case .double(let double): double
+            case .int(let int): int
+            case .uint(let uint): uint
+            case .string(let string): string
             }
         }
 
         public var description: String {
             switch self {
-            case .double(let double): return String(double)
-            case .int(let int): return String(int)
-            case .string(let string): return string
+            case .double(let double): String(double)
+            case .int(let int): String(int)
+            case .uint(let uint): String(uint)
+            case .string(let string): string
             }
         }
     }
diff --git a/Tests/GISToolsTests/GeoJson/FeatureTests.swift b/Tests/GISToolsTests/GeoJson/FeatureTests.swift
index a585fc4..4dacd1d 100644
--- a/Tests/GISToolsTests/GeoJson/FeatureTests.swift
+++ b/Tests/GISToolsTests/GeoJson/FeatureTests.swift
@@ -105,4 +105,22 @@ final class FeatureTests: XCTestCase {
         XCTAssertEqual(featureData, feature.asJsonData(prettyPrinted: true))
     }
 
+    func testFeatureIds() throws {
+        XCTAssertEqual(Feature.Identifier(value: Int8(32)), .int(32))
+        XCTAssertEqual(Feature.Identifier(value: Int8(32))?.int64Value, 32)
+        XCTAssertEqual(Feature.Identifier(value: Int8(32))?.uint64Value, 32)
+
+        XCTAssertEqual(Feature.Identifier(value: Int8(-32)), .int(-32))
+        XCTAssertEqual(Feature.Identifier(value: Int8(-32))?.int64Value, -32)
+        XCTAssertNil(Feature.Identifier(value: Int8(-32))?.uint64Value)
+
+        XCTAssertEqual(Feature.Identifier(value: Int64.max), .int(9223372036854775807))
+        XCTAssertEqual(Feature.Identifier(value: Int64.max)?.int64Value, 9223372036854775807)
+
+        // 9223372036854775808 is Int64.max+1
+        XCTAssertEqual(Feature.Identifier(value: UInt64(9223372036854775808)), .uint(9223372036854775808))
+        XCTAssertNil(Feature.Identifier(value: UInt64(9223372036854775808))?.int64Value)
+        XCTAssertEqual(Feature.Identifier(value: UInt64(9223372036854775808))?.uint64Value, 9223372036854775808)
+    }
+
 }