diff --git a/src/Foundation/NSDecimal.cs b/src/Foundation/NSDecimal.cs
index ffb45b0f7858..666dbe1a6941 100644
--- a/src/Foundation/NSDecimal.cs
+++ b/src/Foundation/NSDecimal.cs
@@ -28,6 +28,7 @@
 //
 using System;
 using System.Globalization;
+using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
 
@@ -53,74 +54,117 @@ public struct NSDecimal
 
 #if !COREBUILD
 		[DllImport (Constants.FoundationLibrary)]
-		static extern nint NSDecimalCompare (ref NSDecimal left, ref NSDecimal right);
-		public static NSComparisonResult Compare (ref NSDecimal left, ref NSDecimal right)
+		unsafe static extern nint NSDecimalCompare (NSDecimal* left, NSDecimal* right);
+		public unsafe static NSComparisonResult Compare (ref NSDecimal left, ref NSDecimal right)
 		{
-			return (NSComparisonResult) (long) NSDecimalCompare (ref left, ref right);
+			return (NSComparisonResult) (long) NSDecimalCompare (
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref left),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref right));
 		}
 
 		[DllImport (Constants.FoundationLibrary)]
-		static extern void NSDecimalRound (out NSDecimal result, ref NSDecimal number, nint scale, nuint mode);
-		public static void Round (out NSDecimal result, ref NSDecimal number, nint scale, NSRoundingMode mode)
+		unsafe static extern void NSDecimalRound (NSDecimal* result, NSDecimal* number, nint scale, nuint mode);
+		public unsafe static void Round (out NSDecimal result, ref NSDecimal number, nint scale, NSRoundingMode mode)
 		{
-			NSDecimalRound (out result, ref number, scale, (nuint) (ulong) mode);
+			result = default (NSDecimal);
+			NSDecimalRound (
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref result),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref number),
+				scale,
+				(nuint) (ulong) mode);
 		}
 
 		[DllImport (Constants.FoundationLibrary)]
-		static extern nuint NSDecimalNormalize (ref NSDecimal number1, ref NSDecimal number2);
-		public static NSCalculationError Normalize (ref NSDecimal number1, ref NSDecimal number2)
+		unsafe static extern nuint NSDecimalNormalize (NSDecimal* number1, NSDecimal* number2);
+		public unsafe static NSCalculationError Normalize (ref NSDecimal number1, ref NSDecimal number2)
 		{
-			return (NSCalculationError) (ulong) NSDecimalNormalize (ref number1, ref number2);
+			return (NSCalculationError) (ulong) NSDecimalNormalize (
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref number1),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref number2));
 		}
 
 		[DllImport (Constants.FoundationLibrary)]
-		static extern nuint NSDecimalAdd (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, nuint mode);
-		public static NSCalculationError Add (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, NSRoundingMode mode)
+		static unsafe extern nuint NSDecimalAdd (NSDecimal* result, NSDecimal* left, NSDecimal* right, nuint mode);
+		public unsafe static NSCalculationError Add (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, NSRoundingMode mode)
 		{
-			return (NSCalculationError) (ulong) NSDecimalAdd (out result, ref left, ref right, (nuint) (ulong) mode);
+			result = default (NSDecimal);
+			return (NSCalculationError) (ulong) NSDecimalAdd (
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref result),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref left),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref right),
+				(nuint) (ulong) mode);
 		}
 
 		[DllImport (Constants.FoundationLibrary)]
-		static extern nuint NSDecimalSubtract (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, nuint mode);
-		public static NSCalculationError Subtract (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, NSRoundingMode mode)
+		unsafe static extern nuint NSDecimalSubtract (NSDecimal* result, NSDecimal* left, NSDecimal* right, nuint mode);
+		public unsafe static NSCalculationError Subtract (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, NSRoundingMode mode)
 		{
-			return (NSCalculationError) (ulong) NSDecimalSubtract (out result, ref left, ref right, (nuint) (ulong) mode);
+			result = default (NSDecimal);
+			return (NSCalculationError) (ulong) NSDecimalSubtract (
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref result),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref left),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref right),
+				(nuint) (ulong) mode);
 		}
 
 		[DllImport (Constants.FoundationLibrary)]
-		static extern nuint NSDecimalMultiply (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, nuint mode);
-		public static NSCalculationError Multiply (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, NSRoundingMode mode)
+		static unsafe extern nuint NSDecimalMultiply (NSDecimal* result, NSDecimal* left, NSDecimal* right, nuint mode);
+		public unsafe static NSCalculationError Multiply (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, NSRoundingMode mode)
 		{
-			return (NSCalculationError) (ulong) NSDecimalMultiply (out result, ref left, ref right, (nuint) (ulong) mode);
+			result = default (NSDecimal);
+			return (NSCalculationError) (ulong) NSDecimalMultiply (
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref result),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref left),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref right),
+				(nuint) (ulong) mode);
 		}
 
 		[DllImport (Constants.FoundationLibrary)]
-		static extern nuint NSDecimalDivide (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, nuint mode);
-		public static NSCalculationError Divide (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, NSRoundingMode mode)
+		unsafe static extern nuint NSDecimalDivide (NSDecimal* result, NSDecimal* left, NSDecimal* right, nuint mode);
+		public unsafe static NSCalculationError Divide (out NSDecimal result, ref NSDecimal left, ref NSDecimal right, NSRoundingMode mode)
 		{
-			return (NSCalculationError) (ulong) NSDecimalDivide (out result, ref left, ref right, (nuint) (ulong) mode);
+			result = default (NSDecimal);
+			return (NSCalculationError) (ulong) NSDecimalDivide (
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref result),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref left),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref right),
+				(nuint) (ulong) mode);
 		}
 
 		[DllImport (Constants.FoundationLibrary)]
-		static extern nuint NSDecimalPower (out NSDecimal result, ref NSDecimal number, nint power, nuint mode);
-		public static NSCalculationError Power (out NSDecimal result, ref NSDecimal number, nint power, NSRoundingMode mode)
+		unsafe static extern nuint NSDecimalPower (NSDecimal* result, NSDecimal* number, nint power, nuint mode);
+		public unsafe static NSCalculationError Power (out NSDecimal result, ref NSDecimal number, nint power, NSRoundingMode mode)
 		{
-			return (NSCalculationError) (ulong) NSDecimalPower (out result, ref number, power, (nuint) (ulong) mode);
+			result = default (NSDecimal);
+			return (NSCalculationError) (ulong) NSDecimalPower (
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref result),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref number),
+				power,
+				(nuint) (ulong) mode);
 		}
 
 		[DllImport (Constants.FoundationLibrary)]
-		static extern nuint NSDecimalMultiplyByPowerOf10 (out NSDecimal result, ref NSDecimal number, short power10, nuint mode);
-		public static NSCalculationError MultiplyByPowerOf10 (out NSDecimal result, ref NSDecimal number, short power10, NSRoundingMode mode)
+		unsafe static extern nuint NSDecimalMultiplyByPowerOf10 (NSDecimal* result, NSDecimal* number, short power10, nuint mode);
+		public unsafe static NSCalculationError MultiplyByPowerOf10 (out NSDecimal result, ref NSDecimal number, short power10, NSRoundingMode mode)
 		{
-			return (NSCalculationError) (ulong) NSDecimalMultiplyByPowerOf10 (out result, ref number, power10, (nuint) (ulong) mode);
+			result = default (NSDecimal);
+			return (NSCalculationError) (ulong) NSDecimalMultiplyByPowerOf10 (
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref result),
+				(NSDecimal *) Unsafe.AsPointer<NSDecimal> (ref number),
+				power10,
+				(nuint) (ulong) mode);
 		}
 
 		[DllImport (Constants.FoundationLibrary)]
-		static extern IntPtr NSDecimalString (ref NSDecimal value, /* _Nullable */ IntPtr locale);
+		unsafe static extern IntPtr NSDecimalString (NSDecimal* value, /* _Nullable */ IntPtr locale);
 
 		public override string ToString ()
 		{
-			return new NSString (NSDecimalString (ref this, NSLocale.CurrentLocale.Handle));
+			unsafe {
+				fixed (NSDecimal* self = &this) {
+					return new NSString (NSDecimalString (self, NSLocale.CurrentLocale.Handle));
+				}
+			}
 		}
 
 		public static NSDecimal operator + (NSDecimal left, NSDecimal right)
diff --git a/tests/cecil-tests/BlittablePInvokes.KnownFailures.cs b/tests/cecil-tests/BlittablePInvokes.KnownFailures.cs
index 25cee30bd483..cc4301dfecc1 100644
--- a/tests/cecil-tests/BlittablePInvokes.KnownFailures.cs
+++ b/tests/cecil-tests/BlittablePInvokes.KnownFailures.cs
@@ -721,8 +721,6 @@ public partial class BlittablePInvokes {
 			"System.IntPtr CoreText.CTRunDelegate::CTRunDelegateCreate(CoreText.CTRunDelegateCallbacks&,System.IntPtr)",
 			"System.IntPtr CoreVideo.CVBuffer::CVBufferCopyAttachment(System.IntPtr,System.IntPtr,CoreVideo.CVAttachmentMode&)",
 			"System.IntPtr CoreVideo.CVBuffer::CVBufferGetAttachment(System.IntPtr,System.IntPtr,CoreVideo.CVAttachmentMode&)",
-			"System.IntPtr Foundation.NSDecimal::NSDecimalCompare(Foundation.NSDecimal&,Foundation.NSDecimal&)",
-			"System.IntPtr Foundation.NSDecimal::NSDecimalString(Foundation.NSDecimal&,System.IntPtr)",
 			"System.IntPtr Foundation.NSSearchPath::NSSearchPathForDirectoriesInDomains(System.UIntPtr,System.UIntPtr,System.Boolean)",
 			"System.IntPtr Foundation.NSThread::xamarin_init_nsthread(System.IntPtr,System.Boolean,System.IntPtr,System.IntPtr,System.IntPtr)",
 			"System.IntPtr GameController.GCExtendedGamepadSnapshotData::NSDataFromGCExtendedGamepadSnapshotData(GameController.GCExtendedGamepadSnapshotData&)",
@@ -760,13 +758,6 @@ public partial class BlittablePInvokes {
 			"System.Runtime.InteropServices.NFloat MediaAccessibility.MACaptionAppearance::MACaptionAppearanceGetRelativeCharacterSize(System.IntPtr,System.IntPtr&)",
 			"System.Runtime.InteropServices.NFloat MediaAccessibility.MACaptionAppearance::MACaptionAppearanceGetWindowOpacity(System.IntPtr,System.IntPtr&)",
 			"System.Runtime.InteropServices.NFloat MediaAccessibility.MACaptionAppearance::MACaptionAppearanceGetWindowRoundedCornerRadius(System.IntPtr,System.IntPtr&)",
-			"System.UIntPtr Foundation.NSDecimal::NSDecimalAdd(Foundation.NSDecimal&,Foundation.NSDecimal&,Foundation.NSDecimal&,System.UIntPtr)",
-			"System.UIntPtr Foundation.NSDecimal::NSDecimalDivide(Foundation.NSDecimal&,Foundation.NSDecimal&,Foundation.NSDecimal&,System.UIntPtr)",
-			"System.UIntPtr Foundation.NSDecimal::NSDecimalMultiply(Foundation.NSDecimal&,Foundation.NSDecimal&,Foundation.NSDecimal&,System.UIntPtr)",
-			"System.UIntPtr Foundation.NSDecimal::NSDecimalMultiplyByPowerOf10(Foundation.NSDecimal&,Foundation.NSDecimal&,System.Int16,System.UIntPtr)",
-			"System.UIntPtr Foundation.NSDecimal::NSDecimalNormalize(Foundation.NSDecimal&,Foundation.NSDecimal&)",
-			"System.UIntPtr Foundation.NSDecimal::NSDecimalPower(Foundation.NSDecimal&,Foundation.NSDecimal&,System.IntPtr,System.UIntPtr)",
-			"System.UIntPtr Foundation.NSDecimal::NSDecimalSubtract(Foundation.NSDecimal&,Foundation.NSDecimal&,Foundation.NSDecimal&,System.UIntPtr)",
 			"System.Void AppKit.NSCell::NSDrawNinePartImage(CoreGraphics.CGRect,System.IntPtr,System.IntPtr,System.IntPtr,System.IntPtr,System.IntPtr,System.IntPtr,System.IntPtr,System.IntPtr,System.IntPtr,System.IntPtr,System.Runtime.InteropServices.NFloat,System.Boolean)",
 			"System.Void AppKit.NSCell::NSDrawThreePartImage(CoreGraphics.CGRect,System.IntPtr,System.IntPtr,System.IntPtr,System.Boolean,System.IntPtr,System.Runtime.InteropServices.NFloat,System.Boolean)",
 			"System.Void CoreFoundation.CFBundle::CFBundleGetPackageInfo(System.IntPtr,System.UInt32&,System.UInt32&)",
@@ -794,7 +785,6 @@ public partial class BlittablePInvokes {
 			"System.Void CoreText.CTFontManager::CTFontManagerRegisterFontsWithAssetNames(System.IntPtr,System.IntPtr,CoreText.CTFontManagerScope,System.Boolean,ObjCRuntime.BlockLiteral*)",
 			"System.Void CoreText.CTFontManager::CTFontManagerRegisterFontURLs(System.IntPtr,CoreText.CTFontManagerScope,System.Boolean,ObjCRuntime.BlockLiteral*)",
 			"System.Void CoreVideo.CVPixelBuffer::CVPixelBufferGetExtendedPixels(System.IntPtr,System.UIntPtr&,System.UIntPtr&,System.UIntPtr&,System.UIntPtr&)",
-			"System.Void Foundation.NSDecimal::NSDecimalRound(Foundation.NSDecimal&,Foundation.NSDecimal&,System.IntPtr,System.UIntPtr)",
 			"System.Void Foundation.NSObject::xamarin_release_managed_ref(System.IntPtr,System.Boolean)",
 			"System.Void ImageIO.CGImageSource::CGImageSourceUpdateData(System.IntPtr,System.IntPtr,System.Boolean)",
 			"System.Void ImageIO.CGImageSource::CGImageSourceUpdateDataProvider(System.IntPtr,System.IntPtr,System.Boolean)",