diff --git a/src/Uno.UI/UI/Xaml/SpecializedResourceDictionary.cs b/src/Uno.UI/UI/Xaml/SpecializedResourceDictionary.cs
index 7acf98e22b09..2becd2b2878a 100644
--- a/src/Uno.UI/UI/Xaml/SpecializedResourceDictionary.cs
+++ b/src/Uno.UI/UI/Xaml/SpecializedResourceDictionary.cs
@@ -14,6 +14,7 @@
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 using System.Runtime.Serialization;
 using Uno.Foundation;
 
@@ -117,7 +118,7 @@ public static implicit operator ResourceKey(Type key)
 		private Entry[] _entries;
 #if TARGET_64BIT
 		private ulong _fastModMultiplier;
-		private static bool Is64Bits = IntPtr.Size >= 8
+		private static bool Is64Bits = Marshal.SizeOf(typeof(IntPtr)) >= 8
 #if __WASM__
 			|| WebAssemblyRuntime.IsWebAssembly;
 #else