diff --git a/Sources/Library/Schema/Values/String.Encoding+JSONCodable.swift b/Sources/Library/Schema/Values/String.Encoding+JSONCodable.swift
index 3d4ce80..cdb27c3 100644
--- a/Sources/Library/Schema/Values/String.Encoding+JSONCodable.swift
+++ b/Sources/Library/Schema/Values/String.Encoding+JSONCodable.swift
@@ -96,7 +96,8 @@ extension String.Encoding: XCJSON.Codable {
         if let stringRepresentation {
             try stringRepresentation.encode(with: coder)
         } else {
-            try Int(rawValue).encode(with: coder)
+            let value = try Int(exactly: rawValue).unwrap(orThrow: "Unsupported text encoding \(rawValue)")
+            try value.encode(with: coder)
         }
     }
 
@@ -104,7 +105,9 @@ extension String.Encoding: XCJSON.Codable {
         if coder.currentNodeType == .string {
             self = try StringRepresentation(with: coder).memoryRepresentation
         } else {
-            self = try Self(rawValue: UInt(Int(with: coder)))
+            let value = try Int(with: coder)
+            let rawValue = try UInt(exactly: value).unwrap(orThrow: "Invalid text encoding \(value)")
+            self = Self(rawValue: rawValue)
         }
     }
 }
diff --git a/Sources/Tests/TextEncodingTests.swift b/Sources/Tests/TextEncodingTests.swift
new file mode 100644
index 0000000..9f1038b
--- /dev/null
+++ b/Sources/Tests/TextEncodingTests.swift
@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2026 Apple Inc. and the xcode-project-format project authors
+//
+// Licensed under Apache License v2.0
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+
+import XcodeProjectFormat
+import Foundation
+import Testing
+
+struct TextEncodingTests {
+    @Test func decodingAnOutOfRangeIntegerThrows() {
+        #expect(throws: NSError.self) {
+            let _: XCSchema.TextEncoding = try XCJSON.Decoder.decode(data: Data("-1".utf8))
+        }
+        #expect(throws: NSError.self) {
+            let _: XCSchema.TextEncoding = try XCJSON.Decoder.decode(data: Data("9223372036854775808".utf8))
+        }
+    }
+
+    @Test func encodingAnOutOfRangeRawValueThrows() {
+        #expect(throws: NSError.self) {
+            _ = try XCJSON.Encoder.data(for: XCSchema.TextEncoding(rawValue: String.Encoding(rawValue: UInt.max)), options: .defaultOptions)
+        }
+    }
+}