diff --git a/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/CompExactlyDependsOn.cs b/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/CompExactlyDependsOn.cs
deleted file mode 100644
index 3169bd22b42d18..00000000000000
--- a/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/CompExactlyDependsOn.cs
+++ /dev/null
@@ -1,18 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-namespace System.Runtime.CompilerServices
-{
-    // Use this attribute to indicate that a function should only be compiled into a Ready2Run
-    // binary if the associated type will always have a well defined value for its IsSupported property
-    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Constructor, AllowMultiple = true, Inherited = false)]
-    internal sealed class CompExactlyDependsOnAttribute : Attribute
-    {
-        public CompExactlyDependsOnAttribute(Type intrinsicsTypeUsedInHelperFunction)
-        {
-            IntrinsicsTypeUsedInHelperFunction = intrinsicsTypeUsedInHelperFunction;
-        }
-
-        public Type IntrinsicsTypeUsedInHelperFunction { get; }
-    }
-}
diff --git a/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/CompExactlyDependsOnAttribute.cs b/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/CompExactlyDependsOnAttribute.cs
index 3169bd22b42d18..3ea457e7c5f3a4 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/CompExactlyDependsOnAttribute.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/CompExactlyDependsOnAttribute.cs
@@ -1,11 +1,16 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics;
+
 namespace System.Runtime.CompilerServices
 {
     // Use this attribute to indicate that a function should only be compiled into a Ready2Run
     // binary if the associated type will always have a well defined value for its IsSupported property
     [AttributeUsage(AttributeTargets.Method | AttributeTargets.Constructor, AllowMultiple = true, Inherited = false)]
+#if MONO
+    [Conditional("unnecessary")] // Mono doesn't use Ready2Run so we can remove this attribute to reduce size
+#endif
     internal sealed class CompExactlyDependsOnAttribute : Attribute
     {
         public CompExactlyDependsOnAttribute(Type intrinsicsTypeUsedInHelperFunction)