diff --git a/Sources/Protocols.swift b/Sources/Protocols.swift
index 4f581b5c..e9133b8e 100644
--- a/Sources/Protocols.swift
+++ b/Sources/Protocols.swift
@@ -32,7 +32,9 @@ public protocol Container {
 
 public protocol ContainerEntry {
 
-    var name: String? { get }
+    var name: String { get }
+    var size: Int { get }
+    var isDirectory: Bool { get }
 
     func data() throws -> Data
 
diff --git a/Sources/TarContainer.swift b/Sources/TarContainer.swift
index a5d167a3..4eac3a42 100644
--- a/Sources/TarContainer.swift
+++ b/Sources/TarContainer.swift
@@ -25,10 +25,14 @@ public enum TarError: Error {
 public class TarEntry: ContainerEntry {
 
     /// Name of the file or directory.
-    public var name: String? {
+    public var name: String {
         return (self.fileNamePrefix ?? "") + (self.fileName ?? "")
     }
 
+    public var isDirectory: Bool {
+        return false // TODO: Implement.
+    }
+
     public let mode: Int?
     public let ownerID: Int?
     public let groupID: Int?
diff --git a/Tests/TarTests.swift b/Tests/TarTests.swift
index f0db4448..907842c5 100644
--- a/Tests/TarTests.swift
+++ b/Tests/TarTests.swift
@@ -27,13 +27,11 @@ class TarTests: XCTestCase {
             return
         }
 
-        guard let entry = result[0] as? TarEntry else {
-            XCTFail("Unable to convert to TarEntry.")
-            return
-        }
-
-        XCTAssertEqual(entry.name, "test5.answer")
-        XCTAssertEqual(entry.data(), Data())
+        XCTAssertEqual(result.count, 1)
+        XCTAssertEqual(result[0].name, "test5.answer")
+        XCTAssertEqual(result[0].size, 0)
+        XCTAssertEqual(result[0].isDirectory, false)
+        XCTAssertEqual(try? result[0].data(), Data())
     }
 
 }