diff --git a/ICSharpCode.NRefactory.Tests/CSharp/Resolver/BinaryOperatorTests.cs b/ICSharpCode.NRefactory.Tests/CSharp/Resolver/BinaryOperatorTests.cs
index 1b141ecb01..250c2619e4 100644
--- a/ICSharpCode.NRefactory.Tests/CSharp/Resolver/BinaryOperatorTests.cs
+++ b/ICSharpCode.NRefactory.Tests/CSharp/Resolver/BinaryOperatorTests.cs
@@ -388,5 +388,62 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			AssertType(typeof(dynamic), resolver.ResolveBinaryOperator(
 				BinaryOperatorType.NullCoalescing, MakeResult(typeof(string)), MakeResult(typeof(dynamic))));
 		}
+		
+		[Test, Ignore("user-defined operators not yet implemented")]
+		public void LiftedUserDefined()
+		{
+			AssertType(typeof(TimeSpan), resolver.ResolveBinaryOperator(
+				BinaryOperatorType.Subtract, MakeResult(typeof(DateTime)), MakeResult(typeof(DateTime))));
+			AssertType(typeof(TimeSpan?), resolver.ResolveBinaryOperator(
+				BinaryOperatorType.Subtract, MakeResult(typeof(DateTime?)), MakeResult(typeof(DateTime))));
+			AssertType(typeof(TimeSpan?), resolver.ResolveBinaryOperator(
+				BinaryOperatorType.Subtract, MakeResult(typeof(DateTime)), MakeResult(typeof(DateTime?))));
+			AssertType(typeof(TimeSpan?), resolver.ResolveBinaryOperator(
+				BinaryOperatorType.Subtract, MakeResult(typeof(DateTime?)), MakeResult(typeof(DateTime?))));
+		}
+		
+		[Test, Ignore("user-defined operators not yet implemented")]
+		public void UserDefinedNeedsLiftingDueToImplicitConversion()
+		{
+			string program = @"struct S {}
+struct A {
+	public static implicit operator S?(A a) { return null; }
+	
+	public static S operator +(A a, S s) { return s; }
+}
+class Test {
+	void M(A a) {
+		var s = $a + a$;
+	}
+}
+";
+			MemberResolveResult trr = Resolve<MemberResolveResult>(program);
+			Assert.IsFalse(trr.IsError);
+			Assert.AreEqual("A.op_Addition", trr.Member.FullName);
+			// even though we're calling the lifted operator, trr.Member should be the original operator method
+			Assert.AreEqual("S", trr.Member.ReturnType.Resolve(context).ReflectionName);
+			Assert.AreEqual("System.Nullable`1[[S]]", trr.Type.ReflectionName);
+		}
+		
+		[Test, Ignore("user-defined operators not yet implemented")]
+		public void ThereIsNoLiftedOperatorsForClasses()
+		{
+			string program = @"struct S {}
+class A {
+	public static implicit operator S?(A a) { return null; }
+	
+	public static S operator +(A a, S s) { return s; }
+}
+class Test {
+	void M(A a) {
+		var s = $a + a$;
+	}
+}
+";
+			MemberResolveResult trr = Resolve<MemberResolveResult>(program);
+			Assert.IsTrue(trr.IsError); // cannot convert from A to S
+			Assert.AreEqual("A.op_Addition", trr.Member.FullName);
+			Assert.AreEqual("S", trr.Type.ReflectionName);
+		}
 	}
 }
diff --git a/ICSharpCode.NRefactory/CSharp/Resolver/MemberLookup.cs b/ICSharpCode.NRefactory/CSharp/Resolver/MemberLookup.cs
index d2f349f74f..7d857b6111 100644
--- a/ICSharpCode.NRefactory/CSharp/Resolver/MemberLookup.cs
+++ b/ICSharpCode.NRefactory/CSharp/Resolver/MemberLookup.cs
@@ -25,9 +25,10 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 			// C# 4.0 spec, §7.4 member lookup
 			if (member is IEvent || member is IMethod)
 				return true;
-			if (member.ReturnType == SharedTypes.Dynamic)
+			IType returnType = member.ReturnType.Resolve(context);
+			if (returnType == SharedTypes.Dynamic)
 				return true;
-			return member.ReturnType.Resolve(context).IsDelegate();
+			return returnType.IsDelegate();
 		}
 		#endregion
 		
diff --git a/ICSharpCode.NRefactory/ICSharpCode.NRefactory.csproj b/ICSharpCode.NRefactory/ICSharpCode.NRefactory.csproj
index 8877f27f5d..1213653727 100644
--- a/ICSharpCode.NRefactory/ICSharpCode.NRefactory.csproj
+++ b/ICSharpCode.NRefactory/ICSharpCode.NRefactory.csproj
@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" DefaultTargets="Build">
   <PropertyGroup>
     <ProjectGuid>{3B2A5653-EC97-4001-BB9B-D90F1AF2C371}</ProjectGuid>
diff --git a/ICSharpCode.NRefactory/TypeSystem/Implementation/SimpleProjectContent.cs b/ICSharpCode.NRefactory/TypeSystem/Implementation/SimpleProjectContent.cs
index e66ec65289..6cb78cbfaa 100644
--- a/ICSharpCode.NRefactory/TypeSystem/Implementation/SimpleProjectContent.cs
+++ b/ICSharpCode.NRefactory/TypeSystem/Implementation/SimpleProjectContent.cs
@@ -39,7 +39,7 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			get { return readOnlyAssemblyAttributes;  }
 		}
 		
-		void AddRemoveAssemblyAttributes(ICollection<IAttribute> addedAttributes, ICollection<IAttribute> removedAttributes)
+		void AddRemoveAssemblyAttributes(ICollection<IAttribute> removedAttributes, ICollection<IAttribute> addedAttributes)
 		{
 			// API uses ICollection instead of IEnumerable to discourage users from evaluating
 			// the list inside the lock (this method is called inside the write lock)