diff --git a/src/AddIns/Misc/Debugger/Debugger.Core/Project/Src/Control/Module.cs b/src/AddIns/Misc/Debugger/Debugger.Core/Project/Src/Control/Module.cs
index 28e697b10f..233c509ef0 100644
--- a/src/AddIns/Misc/Debugger/Debugger.Core/Project/Src/Control/Module.cs
+++ b/src/AddIns/Misc/Debugger/Debugger.Core/Project/Src/Control/Module.cs
@@ -172,6 +172,37 @@ namespace Debugger
 			symReader = metaData.GetSymReader(fullPath, null);
 			
 			JMCStatus = SymbolsLoaded;
+			
+			FindNonUserCode();
+		}
+		
+		/// <summary>
+		/// Finds all classes and methods marked with DebuggerNonUserCode attribute
+		/// and it marks them for JMC so that they are not stepped into
+		/// </summary>
+		void FindNonUserCode()
+		{
+			if (this.SymbolsLoaded) {
+				foreach(CustomAttributeProps ca in metaData.EnumCustomAttributeProps(0, 0)) {
+					MemberRefProps constructorMethod = metaData.GetMemberRefProps(ca.Type);
+					TypeRefProps attributeType = metaData.GetTypeRefProps(constructorMethod.DeclaringType);
+					if (attributeType.Name == "System.Diagnostics.DebuggerStepThroughAttribute" ||
+					    attributeType.Name == "System.Diagnostics.DebuggerNonUserCodeAttribute")
+					{
+						if (ca.Owner >> 24 == 0x02) { // TypeDef
+							ICorDebugClass2 corClass = corModule.GetClassFromToken(ca.Owner).CastTo<ICorDebugClass2>();
+							corClass.SetJMCStatus(0 /* false */);
+							this.Process.TraceMessage("Class {0} marked as non-user code", metaData.GetTypeDefProps(ca.Owner).Name);
+						}
+						if (ca.Owner >> 24 == 0x06) { // MethodDef
+							ICorDebugFunction2 corFunction = corModule.GetFunctionFromToken(ca.Owner).CastTo<ICorDebugFunction2>();
+							corFunction.SetJMCStatus(0 /* false */);
+							MethodProps methodProps = metaData.GetMethodProps(ca.Owner);
+							this.Process.TraceMessage("Function {0}.{1} marked as non-user code", metaData.GetTypeDefProps(methodProps.ClassToken).Name, methodProps.Name);
+						}
+					}
+				}
+			}
 		}
 		
 		public void ApplyChanges(byte[] metadata, byte[] il)
diff --git a/src/AddIns/Misc/Debugger/Debugger.Tests/Project/Debugger.Tests.csproj b/src/AddIns/Misc/Debugger/Debugger.Tests/Project/Debugger.Tests.csproj
index 95740f7c88..71f83b60a0 100644
--- a/src/AddIns/Misc/Debugger/Debugger.Tests/Project/Debugger.Tests.csproj
+++ b/src/AddIns/Misc/Debugger/Debugger.Tests/Project/Debugger.Tests.csproj
@@ -26,7 +26,7 @@
     <DefineConstants>DEBUG;TRACE;TEST_CODE</DefineConstants>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
-    <DefineConstants>TRACE</DefineConstants>
+    <DefineConstants>TRACE;TEST_CODE</DefineConstants>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
diff --git a/src/AddIns/Misc/Debugger/Debugger.Tests/Project/Src/TestPrograms/DebuggerAttributes.cs b/src/AddIns/Misc/Debugger/Debugger.Tests/Project/Src/TestPrograms/DebuggerAttributes.cs
index 7a497e0e6b..aa616d1ea5 100644
--- a/src/AddIns/Misc/Debugger/Debugger.Tests/Project/Src/TestPrograms/DebuggerAttributes.cs
+++ b/src/AddIns/Misc/Debugger/Debugger.Tests/Project/Src/TestPrograms/DebuggerAttributes.cs
@@ -17,6 +17,7 @@ namespace Debugger.Tests.TestPrograms
 			System.Diagnostics.Debug.WriteLine("Start");
 			System.Diagnostics.Debugger.Break();
 			Internal();
+			IgnoredClass.Internal();
 			System.Diagnostics.Debug.WriteLine("End");
 		}
 		
@@ -25,11 +26,22 @@ namespace Debugger.Tests.TestPrograms
 		{
 			System.Diagnostics.Debug.WriteLine("Internal");
 		}
+		
+		[DebuggerNonUserCode]
+		public class IgnoredClass
+		{
+			public static void Internal()
+			{
+				System.Diagnostics.Debug.WriteLine("Internal");
+			}
+		}
 	}
 }
 
 #if TEST_CODE
 namespace Debugger.Tests {
+	using NUnit.Framework;
+	using Debugger.Wrappers.CorDebug;
 	using Debugger.Wrappers.MetaData;
 	
 	public partial class DebuggerTests
@@ -38,17 +50,13 @@ namespace Debugger.Tests {
 		public void DebuggerAttributes()
 		{
 			StartTest("DebuggerAttributes.cs");
-			process.SelectedStackFrame.StepOver();
+			
 			process.SelectedStackFrame.StepInto();
-			Module module = process.SelectedStackFrame.MethodInfo.Module;
-			foreach(ModuleRefProps mRef in module.MetaData.EnumModuleRefProps()) {
-				
-			}
-			uint typeRef = module.MetaData.FindTypeRef(0, "System.Diagnostics.DebuggerStepThroughAttribute");
-			foreach(CustomAttributeProps ca in module.MetaData.EnumCustomAttributeProps(0, 0)) {
-				MemberRefProps memProps = module.MetaData.GetMemberRefProps(ca.Type);
-				TypeRefProps typeDefProps = module.MetaData.GetTypeRefProps(memProps.DeclaringType);
-			}
+			process.SelectedStackFrame.StepInto();
+			Assert.AreEqual(process.SelectedStackFrame.MethodInfo.Name, "Main");
+			process.SelectedStackFrame.StepInto();
+			Assert.AreEqual(process.SelectedStackFrame.MethodInfo.Name, "Main");
+			
 			EndTest();
 		}
 	}
@@ -68,8 +76,10 @@ namespace Debugger.Tests {
     <LogMessage>Start\r\n</LogMessage>
     <DebuggingPaused>Break</DebuggingPaused>
     <DebuggingPaused>StepComplete</DebuggingPaused>
+    <LogMessage>Internal\r\n</LogMessage>
     <DebuggingPaused>StepComplete</DebuggingPaused>
     <LogMessage>Internal\r\n</LogMessage>
+    <DebuggingPaused>StepComplete</DebuggingPaused>
     <LogMessage>End\r\n</LogMessage>
     <ProcessExited />
   </Test>