diff --git a/Sources/Plot/API/Indentation.swift b/Sources/Plot/API/Indentation.swift
index de58609..6f65e59 100644
--- a/Sources/Plot/API/Indentation.swift
+++ b/Sources/Plot/API/Indentation.swift
@@ -7,7 +7,7 @@
 import Foundation
 
 /// A representation of a kind of indentation at a given level.
-public struct Indentation {
+public struct Indentation: Codable, Equatable {
     /// The kind of the indentation (see `Kind`).
     public var kind: Kind
     /// The level of the indentation (0 = root).
@@ -22,7 +22,7 @@ public struct Indentation {
 public extension Indentation {
     /// Enum defining various kinds of indentation that a document
     /// can be rendered using.
-    enum Kind {
+    enum Kind: Equatable {
         /// Each level should be indented by a given number of tabs.
         case tabs(Int)
         /// Each level should be indented by a given number of spaces.
@@ -56,3 +56,42 @@ extension Indentation.Kind: CustomStringConvertible {
         }
     }
 }
+
+extension Indentation.Kind: Codable {
+    private enum CodingKeys: CodingKey {
+        case kind
+        case count
+    }
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        let kind = try container.decode(String.self, forKey: .kind)
+        let count = try container.decode(Int.self, forKey: .count)
+
+        switch kind {
+        case "tabs":
+            self = .tabs(count)
+        case "spaces":
+            self = .spaces(count)
+        default:
+            throw DecodingError.dataCorruptedError(
+                forKey: CodingKeys.kind,
+                in: container,
+                debugDescription: "'\(kind)' is not an indentation kind"
+            )
+        }
+    }
+
+    public func encode(to encoder: Encoder) throws {
+        var container = encoder.container(keyedBy: CodingKeys.self)
+
+        switch self {
+        case .tabs(let count):
+            try container.encode("tabs", forKey: .kind)
+            try container.encode(count, forKey: .count)
+        case .spaces(let count):
+            try container.encode("spaces", forKey: .kind)
+            try container.encode(count, forKey: .count)
+        }
+    }
+}
diff --git a/Sources/Plot/API/PodcastType.swift b/Sources/Plot/API/PodcastType.swift
index ac5975b..7138ba3 100644
--- a/Sources/Plot/API/PodcastType.swift
+++ b/Sources/Plot/API/PodcastType.swift
@@ -7,7 +7,7 @@
 import Foundation
 
 /// Enum describing various podcast types supported by Apple Podcasts.
-public enum PodcastType: String {
+public enum PodcastType: String, Codable {
     case episodic
     case serial
 }
diff --git a/Tests/PlotTests/IndentationTests.swift b/Tests/PlotTests/IndentationTests.swift
new file mode 100644
index 0000000..87d0267
--- /dev/null
+++ b/Tests/PlotTests/IndentationTests.swift
@@ -0,0 +1,27 @@
+import XCTest
+import Plot
+
+final class IndentationTests: XCTestCase {
+    func testSpacesCoding() throws {
+        let indentation = Indentation(kind: .spaces(4))
+        let data = try JSONEncoder().encode(indentation)
+        let decoded = try JSONDecoder().decode(Indentation.self, from: data)
+        XCTAssertEqual(indentation, decoded)
+    }
+
+    func testTabsCoding() throws {
+        let indentation = Indentation(kind: .tabs(1))
+        let data = try JSONEncoder().encode(indentation)
+        let decoded = try JSONDecoder().decode(Indentation.self, from: data)
+        XCTAssertEqual(indentation, decoded)
+    }
+}
+
+extension IndentationTests {
+    static var allTests: Linux.TestList<IndentationTests> {
+        [
+            ("testSpacesCoding", testSpacesCoding),
+            ("testTabsCoding", testTabsCoding)
+        ]
+    }
+}
diff --git a/Tests/PlotTests/LinuxCompatibility.swift b/Tests/PlotTests/LinuxCompatibility.swift
index be2c799..357cecb 100644
--- a/Tests/PlotTests/LinuxCompatibility.swift
+++ b/Tests/PlotTests/LinuxCompatibility.swift
@@ -31,6 +31,8 @@ internal extension Linux {
 #if canImport(ObjectiveC)
 internal final class LinuxVerificationTests: XCTestCase {
     func testAllTestsRunOnLinux() {
+        var totalLinuxTestCount = 0
+
         for testCase in allTests() {
             let type = testCase.testCaseClass
 
@@ -49,7 +51,19 @@ internal final class LinuxVerificationTests: XCTestCase {
                     """)
                 }
             }
+
+            totalLinuxTestCount += linuxTestNames.count
         }
+
+        XCTAssertEqual(
+            XCTestSuite.default.testCaseCount - 1,
+            totalLinuxTestCount,
+            """
+            Linux and Apple Platforms test counts are not equal.
+            Perhaps you added a new test case class?
+            If so, you need to add it in XCTestManifests.swift.
+            """
+        )
     }
 }
 #endif
diff --git a/Tests/PlotTests/XCTestManifests.swift b/Tests/PlotTests/XCTestManifests.swift
index 8253bfa..6ba32a2 100644
--- a/Tests/PlotTests/XCTestManifests.swift
+++ b/Tests/PlotTests/XCTestManifests.swift
@@ -11,6 +11,7 @@ public func allTests() -> [Linux.TestCase] {
         Linux.makeTestCase(using: ControlFlowTests.allTests),
         Linux.makeTestCase(using: DocumentTests.allTests),
         Linux.makeTestCase(using: HTMLTests.allTests),
+        Linux.makeTestCase(using: IndentationTests.allTests),
         Linux.makeTestCase(using: NodeTests.allTests),
         Linux.makeTestCase(using: PodcastFeedTests.allTests),
         Linux.makeTestCase(using: RSSTests.allTests),