diff --git a/src/Vision/VNUtils.cs b/src/Vision/VNUtils.cs
index 7ec920ce8d06..ecfe6bcd1441 100644
--- a/src/Vision/VNUtils.cs
+++ b/src/Vision/VNUtils.cs
@@ -37,8 +37,12 @@ public static partial class VNUtils {
 		public static CGRect NormalizedIdentityRect { get; } = Dlfcn.GetCGRect (Libraries.Vision.Handle, "VNNormalizedIdentityRect");
 
 		[DllImport (Constants.VisionLibrary, EntryPoint = "VNNormalizedRectIsIdentityRect")]
-		[return: MarshalAs (UnmanagedType.U1)]
-		public static extern bool IsIdentityRect (CGRect rect);
+		static extern byte _IsIdentityRect (CGRect rect);
+
+		public static bool IsIdentityRect (CGRect rect)
+		{
+			return _IsIdentityRect (rect) != 0;
+		}
 
 		[DllImport (Constants.VisionLibrary, EntryPoint = "VNImagePointForNormalizedPoint")]
 		public static extern CGPoint GetImagePoint (CGPoint normalizedPoint, nuint imageWidth, nuint imageHeight);
@@ -120,12 +124,15 @@ public static partial class VNUtils {
 		public static extern CGRect GetNormalizedRect (CGRect imageRect, nuint imageWidth, nuint imageHeight, CGRect regionOfInterest);
 
 		[DllImport ("__Internal", EntryPoint = "xamarin_CGPoint__VNNormalizedFaceBoundingBoxPointForLandmarkPoint_Vector2_CGRect_nuint_nuint_string")]
-		static extern CGPoint VNNormalizedFaceBoundingBoxPointForLandmarkPoint (Vector2 faceLandmarkPoint, CGRect faceBoundingBox, nuint imageWidth, nuint imageHeight, out IntPtr error);
+		unsafe static extern CGPoint VNNormalizedFaceBoundingBoxPointForLandmarkPoint (Vector2 faceLandmarkPoint, CGRect faceBoundingBox, nuint imageWidth, nuint imageHeight, IntPtr* error);
 
 		public static CGPoint GetNormalizedFaceBoundingBoxPoint (Vector2 faceLandmarkPoint, CGRect faceBoundingBox, nuint imageWidth, nuint imageHeight)
 		{
 			IntPtr error;
-			var result = VNNormalizedFaceBoundingBoxPointForLandmarkPoint (faceLandmarkPoint, faceBoundingBox, imageWidth, imageHeight, out error);
+			CGPoint result;
+			unsafe {
+				result = VNNormalizedFaceBoundingBoxPointForLandmarkPoint (faceLandmarkPoint, faceBoundingBox, imageWidth, imageHeight, &error);
+			}
 			if (error != IntPtr.Zero)
 				throw new InvalidOperationException (Marshal.PtrToStringAuto (error));
 
@@ -133,12 +140,15 @@ public static CGPoint GetNormalizedFaceBoundingBoxPoint (Vector2 faceLandmarkPoi
 		}
 
 		[DllImport ("__Internal", EntryPoint = "xamarin_CGPoint__VNImagePointForFaceLandmarkPoint_Vector2_CGRect_nuint_nuint_string")]
-		static extern CGPoint VNImagePointForFaceLandmarkPoint (Vector2 faceLandmarkPoint, CGRect faceBoundingBox, nuint imageWidth, nuint imageHeight, out IntPtr error);
+		unsafe static extern CGPoint VNImagePointForFaceLandmarkPoint (Vector2 faceLandmarkPoint, CGRect faceBoundingBox, nuint imageWidth, nuint imageHeight, IntPtr* error);
 
 		public static CGPoint GetImagePoint (Vector2 faceLandmarkPoint, CGRect faceBoundingBox, nuint imageWidth, nuint imageHeight)
 		{
 			IntPtr error;
-			var result = VNImagePointForFaceLandmarkPoint (faceLandmarkPoint, faceBoundingBox, imageWidth, imageHeight, out error);
+			CGPoint result;
+			unsafe {
+				result = VNImagePointForFaceLandmarkPoint (faceLandmarkPoint, faceBoundingBox, imageWidth, imageHeight, &error);
+			}
 			if (error != IntPtr.Zero)
 				throw new InvalidOperationException (Marshal.PtrToStringAuto (error));
 
diff --git a/tests/cecil-tests/BlittablePInvokes.KnownFailures.cs b/tests/cecil-tests/BlittablePInvokes.KnownFailures.cs
index 25cee30bd483..aa9059974ce6 100644
--- a/tests/cecil-tests/BlittablePInvokes.KnownFailures.cs
+++ b/tests/cecil-tests/BlittablePInvokes.KnownFailures.cs
@@ -157,8 +157,6 @@ public partial class BlittablePInvokes {
 			"CoreFoundation.CFMessagePortSendRequestStatus CoreFoundation.CFMessagePort::CFMessagePortSendRequest(System.IntPtr,System.Int32,System.IntPtr,System.Double,System.Double,System.IntPtr,System.IntPtr&)",
 			"CoreFoundation.CFRunLoopExitReason CoreFoundation.CFRunLoop::CFRunLoopRunInMode(System.IntPtr,System.Double,System.Boolean)",
 			"CoreGraphics.CGAffineTransform CoreGraphics.CGPDFPage::CGPDFPageGetDrawingTransform(System.IntPtr,CoreGraphics.CGPDFBox,CoreGraphics.CGRect,System.Int32,System.Boolean)",
-			"CoreGraphics.CGPoint Vision.VNUtils::VNImagePointForFaceLandmarkPoint(System.Numerics.Vector2,CoreGraphics.CGRect,System.UIntPtr,System.UIntPtr,System.IntPtr&)",
-			"CoreGraphics.CGPoint Vision.VNUtils::VNNormalizedFaceBoundingBoxPointForLandmarkPoint(System.Numerics.Vector2,CoreGraphics.CGRect,System.UIntPtr,System.UIntPtr,System.IntPtr&)",
 			"CoreGraphics.CGRect CoreMedia.CMFormatDescription::CMVideoFormatDescriptionGetCleanAperture(System.IntPtr,System.Boolean)",
 			"CoreGraphics.CGSize CoreMedia.CMFormatDescription::CMVideoFormatDescriptionGetPresentationDimensions(System.IntPtr,System.Boolean,System.Boolean)",
 			"CoreGraphics.CGSize CoreText.CTFramesetter::CTFramesetterSuggestFrameSizeWithConstraints(System.IntPtr,Foundation.NSRange,System.IntPtr,CoreGraphics.CGSize,Foundation.NSRange&)",
@@ -575,7 +573,6 @@ public partial class BlittablePInvokes {
 			"System.Boolean UIKit.UIFloatRange::UIFloatRangeIsInfinite(UIKit.UIFloatRange)",
 			"System.Boolean UIKit.UIVideo::UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(System.IntPtr)",
 			"System.Boolean VideoToolbox.VTDecompressionSession::VTIsHardwareDecodeSupported(CoreMedia.CMVideoCodecType)",
-			"System.Boolean Vision.VNUtils::IsIdentityRect(CoreGraphics.CGRect)",
 			"System.Byte Security.SecProtocolMetadata::sec_protocol_metadata_access_supported_signature_algorithms(System.IntPtr,ObjCRuntime.BlockLiteral*)",
 			"System.Byte* Network.NWEndpoint::nw_endpoint_get_signature(System.IntPtr,System.UIntPtr&)",
 			"System.Char CoreFoundation.CFString::CFStringGetCharacterAtIndex(System.IntPtr,System.IntPtr)",
diff --git a/tests/monotouch-test/Vision/VNUtilsTests.cs b/tests/monotouch-test/Vision/VNUtilsTests.cs
index 3d507180a422..d0e26885348d 100644
--- a/tests/monotouch-test/Vision/VNUtilsTests.cs
+++ b/tests/monotouch-test/Vision/VNUtilsTests.cs
@@ -18,6 +18,12 @@
 using Foundation;
 using Vision;
 
+#if NET
+using Vector2 = global::System.Numerics.Vector2;
+#else
+using Vector2 = global::OpenTK.Vector2;
+#endif
+
 namespace MonoTouchFixtures.Vision {
 
 	[TestFixture]
@@ -54,6 +60,24 @@ public void GetNormalizedRectTest ()
 			var normalizedRect = VNUtils.GetImageRect (new CGRect (2, 34, 5, 67), 8, 90, new CGRect (123, 4, 56, 7));
 			Assert.That (normalizedRect, Is.Not.EqualTo (CGRect.Empty), "VNNormalizedRectForImageRectUsingRegionOfInterest is not empty");
 		}
+
+		[Test]
+		public void GetNormalizedFaceBoundingBoxPointTest ()
+		{
+			var normalizedPoint = VNUtils.GetNormalizedFaceBoundingBoxPoint (new Vector2 (9, 8), new CGRect (3, 14, 15, 92), 2, 11);
+			Assert.That (normalizedPoint, Is.Not.EqualTo (CGPoint.Empty), "VNNormalizedFaceBoundingBoxPointForLandmarkPoint is not empty");
+		}
+
+
+		[Test]
+		public void IsIdentityTest ()
+		{
+			Assert.True (VNUtils.IsIdentityRect (new CGRect (0, 0, 1, 1)), "Identity");
+			Assert.False (VNUtils.IsIdentityRect (new CGRect (0, 0, 2, 2)), "Not Identity A");
+			Assert.False (VNUtils.IsIdentityRect (new CGRect (1, 1, 1, 1)), "Not Identity B");
+			Assert.False (VNUtils.IsIdentityRect (new CGRect (1, 1, 0, 0)), "Not Identity C");
+		}
+
 	}
 }
 #endif