diff --git a/src/Xamarin.Android.Build.Tasks/Utilities/MonoAndroidHelper.cs b/src/Xamarin.Android.Build.Tasks/Utilities/MonoAndroidHelper.cs
index a007664c548..6d694dd0fe9 100644
--- a/src/Xamarin.Android.Build.Tasks/Utilities/MonoAndroidHelper.cs
+++ b/src/Xamarin.Android.Build.Tasks/Utilities/MonoAndroidHelper.cs
@@ -307,8 +307,9 @@ public static bool IsFrameworkAssembly (string assembly, bool checkSdkPath)
 
 		public static bool IsReferenceAssembly (string assembly)
 		{
-			var a = AssemblyDefinition.ReadAssembly (assembly, new ReaderParameters () { InMemory = true, ReadSymbols = false, });
-			return IsReferenceAssembly (a);
+			var rp = new ReaderParameters { ReadSymbols = false };
+			using (var a = AssemblyDefinition.ReadAssembly (assembly, rp))
+				return IsReferenceAssembly (a);
 		}
 
 		public static bool IsReferenceAssembly (AssemblyDefinition assembly)