diff --git a/Source/API/Utils/CrossPlattformGraphics.swift b/Source/API/Utils/CrossPlattformGraphics.swift
index 2001ba9e..1e8562bd 100644
--- a/Source/API/Utils/CrossPlattformGraphics.swift
+++ b/Source/API/Utils/CrossPlattformGraphics.swift
@@ -77,7 +77,7 @@
         public static var topRight: RectCorner = .init(rawValue: 1 << 1)
         public static var bottomLeft: RectCorner = .init(rawValue: 1 << 2)
         public static var bottomRight: RectCorner = .init(rawValue: 1 << 3)
-        public static var allCorners: RectCorner = .init(rawValue: 1 << 4 - 1)
+        public static var allCorners: RectCorner = .init(rawValue: (1 << 4) - 1)
 
         let value: Int
 
diff --git a/Tests/TPPDFTests/Utils/RectCornerTests.swift b/Tests/TPPDFTests/Utils/RectCornerTests.swift
new file mode 100644
index 00000000..6f927197
--- /dev/null
+++ b/Tests/TPPDFTests/Utils/RectCornerTests.swift
@@ -0,0 +1,70 @@
+//
+//  RectCornerTests.swift
+//  TPPDF_Tests
+//
+//  Created by Philip Niedertscheider on 2025-12-29.
+//  Copyright © 2016-2025 techprimate GmbH. All rights reserved.
+//
+
+#if !os(iOS) && !os(tvOS) && !os(watchOS) && !os(visionOS)
+import Testing
+@testable import TPPDF
+
+@Suite("RectCorner Tests")
+struct RectCornerTests {
+    @Test("Individual corner raw values are correct")
+    func testIndividualCornerRawValues() {
+        #expect(RectCorner.topLeft.rawValue == 1)  // 1 << 0 = 0b0001
+        #expect(RectCorner.topRight.rawValue == 2) // 1 << 1 = 0b0010
+        #expect(RectCorner.bottomLeft.rawValue == 4) // 1 << 2 = 0b0100
+        #expect(RectCorner.bottomRight.rawValue == 8) // 1 << 3 = 0b1000
+    }
+
+    @Test("allCorners raw value is correct")
+    func testAllCornersRawValue() {
+        // allCorners should be (1 << 4) - 1 = 16 - 1 = 15 = 0b1111
+        #expect(RectCorner.allCorners.rawValue == 15)
+    }
+
+    @Test("allCorners contains all individual corners")
+    func testAllCornersContainsAllCorners() {
+        #expect(RectCorner.allCorners.contains(.topLeft))
+        #expect(RectCorner.allCorners.contains(.topRight))
+        #expect(RectCorner.allCorners.contains(.bottomLeft))
+        #expect(RectCorner.allCorners.contains(.bottomRight))
+    }
+
+    @Test("Can combine corners using OptionSet operations")
+    func testCombineCorners() {
+        let topCorners: RectCorner = [.topLeft, .topRight]
+        #expect(topCorners.contains(.topLeft))
+        #expect(topCorners.contains(.topRight))
+        #expect(!topCorners.contains(.bottomLeft))
+        #expect(!topCorners.contains(.bottomRight))
+
+        let bottomCorners: RectCorner = [.bottomLeft, .bottomRight]
+        #expect(bottomCorners.contains(.bottomLeft))
+        #expect(bottomCorners.contains(.bottomRight))
+        #expect(!bottomCorners.contains(.topLeft))
+        #expect(!bottomCorners.contains(.topRight))
+    }
+
+    @Test("Can create RectCorner from raw value")
+    func testInitFromRawValue() {
+        let corner = RectCorner(rawValue: 1)
+        #expect(corner.rawValue == 1)
+        #expect(corner == .topLeft)
+
+        let allCornersFromRaw = RectCorner(rawValue: 15)
+        #expect(allCornersFromRaw.rawValue == 15)
+        #expect(allCornersFromRaw == .allCorners)
+    }
+
+    @Test("Union of all individual corners equals allCorners")
+    func testUnionEqualsAllCorners() {
+        let combined: RectCorner = [.topLeft, .topRight, .bottomLeft, .bottomRight]
+        #expect(combined.rawValue == RectCorner.allCorners.rawValue)
+        #expect(combined == .allCorners)
+    }
+}
+#endif