diff --git a/.gitignore b/.gitignore
index f6f5465e..c01c56a8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,4 @@ DerivedData/
 /Package.resolved
 .ci/
 .docc-build/
+.swiftpm
diff --git a/Sources/OpenAPIRuntime/Base/OpenAPIValue.swift b/Sources/OpenAPIRuntime/Base/OpenAPIValue.swift
index 2bb98f4c..a1be0397 100644
--- a/Sources/OpenAPIRuntime/Base/OpenAPIValue.swift
+++ b/Sources/OpenAPIRuntime/Base/OpenAPIValue.swift
@@ -18,6 +18,8 @@ import class Foundation.NSNull
 #else
 @preconcurrency import class Foundation.NSNull
 #endif
+import class Foundation.NSNumber
+import CoreFoundation
 #endif
 
 /// A container for a value represented by JSON Schema.
@@ -139,6 +141,10 @@ public struct OpenAPIValueContainer: Codable, Hashable, Sendable {
             try container.encodeNil()
             return
         }
+        if let nsNumber = value as? NSNumber {
+            try encode(nsNumber, to: &container)
+            return
+        }
         #endif
         switch value {
         case let value as Bool: try container.encode(value)
@@ -156,6 +162,42 @@ public struct OpenAPIValueContainer: Codable, Hashable, Sendable {
             )
         }
     }
+    /// Encodes the provided NSNumber based on its internal representation.
+    /// - Parameters:
+    ///   - value: The NSNumber that boxes one of possibly many different types of values.
+    ///   - container: The container to encode the value in.
+    /// - Throws: An error if the encoding process encounters issues or if the value is invalid.
+    private func encode(_ value: NSNumber, to container: inout any SingleValueEncodingContainer) throws {
+        if value === kCFBooleanTrue {
+            try container.encode(true)
+        } else if value === kCFBooleanFalse {
+            try container.encode(false)
+        } else {
+            #if canImport(ObjectiveC)
+            let nsNumber = value as CFNumber
+            #else
+            let nsNumber = unsafeBitCast(value, to: CFNumber.self)
+            #endif
+            let type = CFNumberGetType(nsNumber)
+            switch type {
+            case .sInt8Type, .charType: try container.encode(value.int8Value)
+            case .sInt16Type, .shortType: try container.encode(value.int16Value)
+            case .sInt32Type, .intType: try container.encode(value.int32Value)
+            case .sInt64Type, .longLongType: try container.encode(value.int64Value)
+            case .float32Type, .floatType: try container.encode(value.floatValue)
+            case .float64Type, .doubleType, .cgFloatType: try container.encode(value.doubleValue)
+            case .nsIntegerType, .longType, .cfIndexType: try container.encode(value.intValue)
+            default:
+                throw EncodingError.invalidValue(
+                    value,
+                    .init(
+                        codingPath: container.codingPath,
+                        debugDescription: "OpenAPIValueContainer cannot encode NSNumber of the underlying type: \(type)"
+                    )
+                )
+            }
+        }
+    }
 
     // MARK: Equatable
 
diff --git a/Tests/OpenAPIRuntimeTests/Base/Test_OpenAPIValue.swift b/Tests/OpenAPIRuntimeTests/Base/Test_OpenAPIValue.swift
index 89a4a5a8..7049502e 100644
--- a/Tests/OpenAPIRuntimeTests/Base/Test_OpenAPIValue.swift
+++ b/Tests/OpenAPIRuntimeTests/Base/Test_OpenAPIValue.swift
@@ -13,11 +13,8 @@
 //===----------------------------------------------------------------------===//
 import XCTest
 #if canImport(Foundation)
-#if canImport(Darwin)
-import class Foundation.NSNull
-#else
-@preconcurrency import class Foundation.NSNull
-#endif
+@preconcurrency import Foundation
+import CoreFoundation
 #endif
 @_spi(Generated) @testable import OpenAPIRuntime
 
@@ -80,8 +77,58 @@ final class Test_OpenAPIValue: Test_Runtime {
             """#
         try _testPrettyEncoded(container, expectedJSON: expectedString)
     }
-    #endif
 
+    func testEncodingNSNumber() throws {
+        func assertEncodedCF(
+            _ value: CFNumber,
+            as encodedValue: String,
+            file: StaticString = #filePath,
+            line: UInt = #line
+        ) throws {
+            #if canImport(ObjectiveC)
+            let nsNumber = value as NSNumber
+            #else
+            let nsNumber = unsafeBitCast(self, to: NSNumber.self)
+            #endif
+            try assertEncoded(nsNumber, as: encodedValue, file: file, line: line)
+        }
+        func assertEncoded(
+            _ value: NSNumber,
+            as encodedValue: String,
+            file: StaticString = #filePath,
+            line: UInt = #line
+        ) throws {
+            let container = try OpenAPIValueContainer(unvalidatedValue: value)
+            let encoder = JSONEncoder()
+            encoder.outputFormatting = .sortedKeys
+            let data = try encoder.encode(container)
+            XCTAssertEqual(String(decoding: data, as: UTF8.self), encodedValue, file: file, line: line)
+        }
+        try assertEncoded(NSNumber(value: true as Bool), as: "true")
+        try assertEncoded(NSNumber(value: false as Bool), as: "false")
+        try assertEncoded(NSNumber(value: 24 as Int8), as: "24")
+        try assertEncoded(NSNumber(value: 24 as Int16), as: "24")
+        try assertEncoded(NSNumber(value: 24 as Int32), as: "24")
+        try assertEncoded(NSNumber(value: 24 as Int64), as: "24")
+        try assertEncoded(NSNumber(value: 24 as Int), as: "24")
+        try assertEncoded(NSNumber(value: 24 as UInt8), as: "24")
+        try assertEncoded(NSNumber(value: 24 as UInt16), as: "24")
+        try assertEncoded(NSNumber(value: 24 as UInt32), as: "24")
+        try assertEncoded(NSNumber(value: 24 as UInt64), as: "24")
+        try assertEncoded(NSNumber(value: 24 as UInt), as: "24")
+        #if canImport(ObjectiveC)
+        try assertEncoded(NSNumber(value: 24 as NSInteger), as: "24")
+        #endif
+        try assertEncoded(NSNumber(value: 24 as CFIndex), as: "24")
+        try assertEncoded(NSNumber(value: 24.1 as Float32), as: "24.1")
+        try assertEncoded(NSNumber(value: 24.1 as Float64), as: "24.1")
+        try assertEncoded(NSNumber(value: 24.1 as Float), as: "24.1")
+        try assertEncoded(NSNumber(value: 24.1 as Double), as: "24.1")
+        XCTAssertThrowsError(try assertEncodedCF(kCFNumberNaN, as: "-"))
+        XCTAssertThrowsError(try assertEncodedCF(kCFNumberNegativeInfinity, as: "-"))
+        XCTAssertThrowsError(try assertEncodedCF(kCFNumberPositiveInfinity, as: "-"))
+    }
+    #endif
     func testEncoding_container_failure() throws {
         struct Foobar: Equatable {}
         XCTAssertThrowsError(try OpenAPIValueContainer(unvalidatedValue: Foobar())) { error in