diff --git a/Debugger/ILSpy.Debugger/Services/Debugger/WindowsDebugger.cs b/Debugger/ILSpy.Debugger/Services/Debugger/WindowsDebugger.cs
index c67b4b35f..ca2217540 100644
--- a/Debugger/ILSpy.Debugger/Services/Debugger/WindowsDebugger.cs
+++ b/Debugger/ILSpy.Debugger/Services/Debugger/WindowsDebugger.cs
@@ -858,7 +858,7 @@ namespace ILSpy.Debugger.Services
 			string fullName = debugType.FullNameWithoutGenericArguments;
 			fullName = fullName.Replace("+", "/");
 			if (DebugData.LoadedAssemblies == null)
-				Continue();
+				throw new NullReferenceException("No DebugData assemblies!");
 			else {
 				// search for type in the current assembly list
 				TypeDefinition typeDef = null;
@@ -896,11 +896,11 @@ namespace ILSpy.Debugger.Services
 						DebuggerService.JumpToCurrentLine(typeDef, line, 0, line, 0);
 					} else {
 						// continue since we cannot find the debugged type
-						StepOver();
+						throw new InvalidOperationException(string.Format("No mapping for {0} for token {1} and offset {2}!", fullName, token, ilOffset));
 					}
 				} else {
 					// continue since we cannot find the debugged type
-					Continue();
+					throw new NullReferenceException(string.Format("The type {0} was not found!", fullName));
 				}
 			}
 		}
diff --git a/ICSharpCode.Decompiler/CodeMappings.cs b/ICSharpCode.Decompiler/CodeMappings.cs
index 53733c7cc..7945a8f4b 100644
--- a/ICSharpCode.Decompiler/CodeMappings.cs
+++ b/ICSharpCode.Decompiler/CodeMappings.cs
@@ -250,7 +250,7 @@ namespace ICSharpCode.Decompiler
 		/// Gets the source code and type name from metadata token and offset.
 		/// </summary>
 		/// <param name="codeMappings">Code mappings storage.</param>
-		/// <param name="currentTypeFullName">Current type name.</param>
+		/// <param name="typeName">Current type name.</param>
 		/// <param name="token">Metadata token.</param>
 		/// <param name="ilOffset">IL offset.</param>
 		/// <param name="typeName">Type definition.</param>
@@ -258,7 +258,7 @@ namespace ICSharpCode.Decompiler
 		/// <remarks>It is possible to exist to different types from different assemblies with the same metadata token.</remarks>
 		public static bool GetSourceCodeFromMetadataTokenAndOffset(
 			this ConcurrentDictionary<string, List<MemberMapping>> codeMappings,
-			string currentTypeFullName,
+			string typeName,
 			uint token,
 			int ilOffset,
 			out TypeDefinition type,
@@ -267,10 +267,14 @@ namespace ICSharpCode.Decompiler
 			type = null;
 			line = 0;
 			
-			if (!codeMappings.ContainsKey(currentTypeFullName))
+			if (codeMappings == null)
+				throw new ArgumentNullException("CodeMappings storage must be valid!");
+			
+			typeName = typeName.Replace("+", "/");
+			if (!codeMappings.ContainsKey(typeName))
 				return false;
 			
-			var mapping = codeMappings[currentTypeFullName].Find(m => m.MetadataToken == token);
+			var mapping = codeMappings[typeName].Find(m => m.MetadataToken == token);
 			if (mapping == null)
 				return false;
 			
diff --git a/ILSpy/Commands/DebuggerCommands.cs b/ILSpy/Commands/DebuggerCommands.cs
index 49b47a40f..ec711f683 100644
--- a/ILSpy/Commands/DebuggerCommands.cs
+++ b/ILSpy/Commands/DebuggerCommands.cs
@@ -242,8 +242,10 @@ namespace ICSharpCode.ILSpy.Commands
 	{
 		public override void Execute(object parameter)
 		{
-			if (CurrentDebugger.IsDebugging && !CurrentDebugger.IsProcessRunning)
+			if (CurrentDebugger.IsDebugging && !CurrentDebugger.IsProcessRunning) {
+				base.Execute(null);
 				CurrentDebugger.StepOver();
+			}
 		}
 	}
 	
@@ -257,8 +259,10 @@ namespace ICSharpCode.ILSpy.Commands
 	{
 		public override void Execute(object parameter)
 		{
-			if (CurrentDebugger.IsDebugging && !CurrentDebugger.IsProcessRunning)
+			if (CurrentDebugger.IsDebugging && !CurrentDebugger.IsProcessRunning) {
+				base.Execute(null);
 				CurrentDebugger.StepOut();
+			}
 		}
 	}