diff --git a/src/AddIns/Misc/Debugger/Debugger.BooInterpreter/Project/Src/DebugeeInterpreterContext.cs b/src/AddIns/Misc/Debugger/Debugger.BooInterpreter/Project/Src/DebugeeInterpreterContext.cs
index c8db2153e9..2b1ef47929 100644
--- a/src/AddIns/Misc/Debugger/Debugger.BooInterpreter/Project/Src/DebugeeInterpreterContext.cs
+++ b/src/AddIns/Misc/Debugger/Debugger.BooInterpreter/Project/Src/DebugeeInterpreterContext.cs
@@ -127,18 +127,20 @@ namespace Debugger
 		void BeforeGetValue(string name)
 		{
 			// PrintLine("BeforeGetValue: " + name);
-			Variable localVar = debugger.LocalVariables[name];
-			if (localVar != null) {
+			try {
+				Variable localVar = debugger.LocalVariables[name];
 				PrintLine("Warning: 'Getting of local variables not implemented'");
+			} catch (DebuggerException) {
 			}
 		}
 		
 		void AfterSetValue(string name)
 		{
 			//PrintLine("AfterSetValue: " + name);
-			Variable localVar = debugger.LocalVariables[name];
-			if (localVar != null) {
+			try {
+				Variable localVar = debugger.LocalVariables[name];
 				PrintLine("Warning: 'Setting of local variables not implemented'");
+			} catch (DebuggerException) {
 			}
 		}
 		
diff --git a/src/AddIns/Misc/Debugger/Debugger.Core/Project/Src/Variables/VariableCollection.cs b/src/AddIns/Misc/Debugger/Debugger.Core/Project/Src/Variables/VariableCollection.cs
index 589ca77449..5da9d6e005 100644
--- a/src/AddIns/Misc/Debugger/Debugger.Core/Project/Src/Variables/VariableCollection.cs
+++ b/src/AddIns/Misc/Debugger/Debugger.Core/Project/Src/Variables/VariableCollection.cs
@@ -102,7 +102,7 @@ namespace Debugger
 						if (v.Name == variableName) return v;
 					}
 				}
-				return null;
+				throw new DebuggerException("Variable \"" + variableName + "\" is not in collection");
 			}
 		}