diff --git a/Advanced Software Engineering/Advanced Software Engineering/Drawer.cs b/Advanced Software Engineering/Advanced Software Engineering/Drawer.cs
index 660e8d5..55dee23 100644
--- a/Advanced Software Engineering/Advanced Software Engineering/Drawer.cs	
+++ b/Advanced Software Engineering/Advanced Software Engineering/Drawer.cs	
@@ -190,7 +190,7 @@ namespace Advanced_Software_Engineering {
         }
 
         public void SetVariable(string name, IValue value) {
-            variables.Add(name, value);
+            variables[name] = value;
         }
 
         public IValue GetVariable(string name) {
diff --git a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/DeclareVariable.cs b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/DeclareVariable.cs
index 374a0a6..9316480 100644
--- a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/DeclareVariable.cs	
+++ b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/DeclareVariable.cs	
@@ -9,9 +9,9 @@ namespace Advanced_Software_Engineering.Verbs.Value {
         private string name;
 
         //Common characters that people might try
-        private char[] illegalCharacters = "1234567890!?/+- \"'@#~;:><,.`¬|[]{}\\£$%^&*()".ToCharArray();
+        private static readonly char[] illegalCharacters = "1234567890!?/+- \"'@#~;:><,.`¬|[]{}\\£$%^&*()".ToCharArray();
 
-        private string[] illegalNames =
+        private static readonly string[] illegalNames =
             { "var",
               "move", "moveto",
               "drawto", "line", "lineto",
@@ -73,6 +73,9 @@ namespace Advanced_Software_Engineering.Verbs.Value {
             if (drawer.CheckVariableExists(name)) throw new Exception("Declaration failed. " + name + " has been declared before");
             if (!CheckName(name)) throw new Exception("'" + name + "' name not allowed");
 
+            //preassign name
+            drawer.SetVariable(name, null);
+
             //for single number assignments ["i", "=", "20"]
             if (assignmentStrings.Length == 3) value = ValueFactory.CreateValue(drawer, assignmentStrings[2]);
 
diff --git a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/IValue.cs b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/IValue.cs
index 6c27245..9ca6a0a 100644
--- a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/IValue.cs	
+++ b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/IValue.cs	
@@ -17,5 +17,7 @@ namespace Advanced_Software_Engineering.Verbs.Value {
         string GetOriginalType();
 
         bool isInitialised();
+
+        IValue Clone();
     }
 }
\ No newline at end of file
diff --git a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/UpdateVariable.cs b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/UpdateVariable.cs
index fbd9049..6502edb 100644
--- a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/UpdateVariable.cs	
+++ b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/UpdateVariable.cs	
@@ -50,7 +50,7 @@ namespace Advanced_Software_Engineering.Verbs.Value {
 
         public void ExecuteVerb() {
             if (!drawer.CheckVariableExists(name)) throw new Exception("Cannot update variable because it is not declared");
-            drawer.SetVariable(name, value);
+            drawer.SetVariable(name, value.Clone());
         }
 
         public string GetDescription() {
diff --git a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueObjects/ColorValue.cs b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueObjects/ColorValue.cs
index 0831036..81c6458 100644
--- a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueObjects/ColorValue.cs	
+++ b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueObjects/ColorValue.cs	
@@ -62,5 +62,9 @@ namespace Advanced_Software_Engineering.Verbs.Value.ValueObjects {
         public bool isInitialised() {
             return true;
         }
+
+        public IValue Clone() {
+            return new ColorValue(this.ToColor());
+        }
     }
 }
\ No newline at end of file
diff --git a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/BoolValue.cs b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/BoolValue.cs
index 43f9213..f6ad676 100644
--- a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/BoolValue.cs	
+++ b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/BoolValue.cs	
@@ -45,5 +45,9 @@ namespace Advanced_Software_Engineering.Verbs.Value.ValueTypes {
         public bool isInitialised() {
             return initialised;
         }
+
+        public IValue Clone() {
+            return new BoolValue(value);
+        }
     }
 }
\ No newline at end of file
diff --git a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/ComparisonValue.cs b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/ComparisonValue.cs
index d5b6f23..53e1739 100644
--- a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/ComparisonValue.cs	
+++ b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/ComparisonValue.cs	
@@ -72,5 +72,9 @@ namespace Advanced_Software_Engineering.Verbs.Value.ValueTypes {
         public int ToInt() {
             return Evaluate().ToInt();
         }
+
+        public IValue Clone() {
+            return new ComparisonValue(value1, value2, op);
+        }
     }
 }
\ No newline at end of file
diff --git a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/DoubleValue.cs b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/DoubleValue.cs
index 34652bc..0a50ab6 100644
--- a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/DoubleValue.cs	
+++ b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/DoubleValue.cs	
@@ -48,5 +48,9 @@ namespace Advanced_Software_Engineering.Verbs.Value.ValueTypes {
         public bool isInitialised() {
             return initialised;
         }
+
+        public IValue Clone() {
+            return new DoubleValue(value);
+        }
     }
 }
\ No newline at end of file
diff --git a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/ExpressionValue.cs b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/ExpressionValue.cs
index a18c564..3a151ed 100644
--- a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/ExpressionValue.cs	
+++ b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/ExpressionValue.cs	
@@ -57,7 +57,7 @@ namespace Advanced_Software_Engineering.Verbs.Value {
         private IValue Evaluate() {
             if (evaluated) return evaluatedValue;
 
-            string outputType = variable1.GetOriginalType();
+            string outputType = variable1.Clone().GetOriginalType();
 
             switch (outputType) {
                 case "bool":
@@ -119,7 +119,7 @@ namespace Advanced_Software_Engineering.Verbs.Value {
         }
 
         public string GetOriginalType() {
-            return variable1.GetOriginalType();
+            return "expression";
         }
 
         public bool isInitialised() {
@@ -141,5 +141,9 @@ namespace Advanced_Software_Engineering.Verbs.Value {
         public int ToInt() {
             return Evaluate().ToInt();
         }
+
+        public IValue Clone() {
+            return Evaluate();
+        }
     }
 }
\ No newline at end of file
diff --git a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/IntValue.cs b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/IntValue.cs
index d266973..3a890f5 100644
--- a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/IntValue.cs	
+++ b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/IntValue.cs	
@@ -63,5 +63,9 @@ namespace Advanced_Software_Engineering.Verbs.Value.ValueTypes {
         public bool isInitialised() {
             return initialised;
         }
+
+        public IValue Clone() {
+            return new IntValue(value);
+        }
     }
 }
\ No newline at end of file
diff --git a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/VariableValue.cs b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/VariableValue.cs
index 7e832f1..a34aa95 100644
--- a/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/VariableValue.cs	
+++ b/Advanced Software Engineering/Advanced Software Engineering/Verbs/Value/ValueTypes/VariableValue.cs	
@@ -44,5 +44,9 @@ namespace Advanced_Software_Engineering.Verbs.Value.ValueTypes {
         public int ToInt() {
             return get().ToInt();
         }
+
+        public IValue Clone() {
+            return new VariableValue(drawer, variableName);
+        }
     }
 }
\ No newline at end of file