diff --git a/ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngine.cs b/ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngine.cs
index 30def5d158..59a02c6fc7 100644
--- a/ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngine.cs
+++ b/ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngine.cs
@@ -242,9 +242,9 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 				var initializerResult = ResolveExpression(p, unit);
 				if (initializerResult != null && initializerResult.Item1.Type.Kind != TypeKind.Unknown) {
 					// check 3 cases:
-					// New initalizer { xpr
-					// Object initializer { prop = val1, field = val2, xpr
-					// Array initializer { new Foo (), a, xpr
+					// 1) New initalizer { xpr
+					// 2) Object initializer { prop = val1, field = val2, xpr
+					// 3) Array initializer { new Foo (), a, xpr
 					// in case 1 all object/array initializer options should be given - in the others not.
 
 					AstNode prev = null;
@@ -256,6 +256,7 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 
 					if (prev != null && !(prev is NamedExpression)) {
 						AddContextCompletion(contextList, GetState(), n, unit);
+						// case 3)
 						return contextList.Result;
 					}
 
@@ -263,12 +264,23 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 						contextList.AddMember(m);
 					}
 
-					if (prev != null && (prev is NamedExpression))
+					if (prev != null && (prev is NamedExpression)) {
+						// case 2)
 						return contextList.Result;
+					}
+
+					// case 1)
+
+					// check if the object is a list, if not only provide object initalizers
+					var list = typeof (System.Collections.IList).ToTypeReference ().Resolve (Compilation);
+					if (initializerResult.Item1.Type.Kind != TypeKind.Array && list != null) {
+						var def = initializerResult.Item1.Type.GetDefinition (); 
+						if (def != null && !def.IsDerivedFrom (list.GetDefinition ()))
+							return contextList.Result;
+					}
 
 					AddContextCompletion(contextList, GetState(), n, unit);
 					return contextList.Result;
-
 				}
 			}
 			return null;
diff --git a/ICSharpCode.NRefactory.Tests/CSharp/CodeCompletion/ObjectInitializerTests.cs b/ICSharpCode.NRefactory.Tests/CSharp/CodeCompletion/ObjectInitializerTests.cs
index f4b4f03897..d75fddec79 100644
--- a/ICSharpCode.NRefactory.Tests/CSharp/CodeCompletion/ObjectInitializerTests.cs
+++ b/ICSharpCode.NRefactory.Tests/CSharp/CodeCompletion/ObjectInitializerTests.cs
@@ -561,6 +561,32 @@ class MyTest
 			}
 			);
 		}
+
+		/// <summary>
+		/// Bug 5126 - Multiple projects including the same files don't update their typesystem properly
+		/// </summary>
+		[Test()]
+		public void TestBug5126()
+		{
+			CodeCompletionBugTests.CombinedProviderTest(
+@"using System;
+using System.Collections.Generic;
+class MyList { public bool MyProp {get;set; }  public bool MyProp2 {get;set; }  }
+class MyTest
+{
+	public void Test ()
+	{
+		$new MyList { n$
+	}
+}
+", provider => {
+				Assert.IsNull(provider.Find("new"), "'new' found.");
+				Assert.IsNotNull(provider.Find("MyProp"), "'MyProp' not found.");
+				Assert.IsNotNull(provider.Find("MyProp2"), "'MyProp2' not found.");
+			}
+			);
+		}
+
 	}
 
 }