diff --git a/src/main/java/com/github/sommeri/less4j/core/ast/ASTCssNode.java b/src/main/java/com/github/sommeri/less4j/core/ast/ASTCssNode.java
index 655719ff..32e14263 100644
--- a/src/main/java/com/github/sommeri/less4j/core/ast/ASTCssNode.java
+++ b/src/main/java/com/github/sommeri/less4j/core/ast/ASTCssNode.java
@@ -146,4 +146,14 @@ public void configureParentToAllChilds() {
     }
   }
 
+  @Override
+  public String toString() {
+    StringBuilder builder = new StringBuilder();
+    builder.append(this.getClass().getSimpleName()).append(" (");
+    builder.append(getSourceLine()).append(":").append(getSourceColumn());
+    builder.append(")");
+
+    return builder.toString();
+  }
+
 }
diff --git a/src/main/java/com/github/sommeri/less4j/core/ast/DetachedRulesetReference.java b/src/main/java/com/github/sommeri/less4j/core/ast/DetachedRulesetReference.java
index bbebde08..76f0d077 100644
--- a/src/main/java/com/github/sommeri/less4j/core/ast/DetachedRulesetReference.java
+++ b/src/main/java/com/github/sommeri/less4j/core/ast/DetachedRulesetReference.java
@@ -12,6 +12,7 @@ public class DetachedRulesetReference extends ASTCssNode {
   
   public DetachedRulesetReference(HiddenTokenAwareTree token, Variable variable) {
     super(token);
+    this.variable = variable;
   }
 
   public Variable getVariable() {
diff --git a/src/main/java/com/github/sommeri/less4j/core/ast/Expression.java b/src/main/java/com/github/sommeri/less4j/core/ast/Expression.java
index 3816c48f..39720fb7 100644
--- a/src/main/java/com/github/sommeri/less4j/core/ast/Expression.java
+++ b/src/main/java/com/github/sommeri/less4j/core/ast/Expression.java
@@ -3,14 +3,36 @@
 import java.util.Collections;
 import java.util.List;
 
+import com.github.sommeri.less4j.core.ast.annotations.NotAstProperty;
+import com.github.sommeri.less4j.core.compiler.scopes.IScope;
 import com.github.sommeri.less4j.core.parser.HiddenTokenAwareTree;
 
-public abstract class Expression extends ASTCssNode {
+public abstract class Expression extends ASTCssNode implements IScopeAware {
+
+  private IScope ownerScope;
 
   public Expression(HiddenTokenAwareTree token) {
     super(token);
   }
 
+  @Override
+  @NotAstProperty
+  public IScope getScope() {
+    return ownerScope;
+  }
+
+  @Override
+  @NotAstProperty
+  public void setScope(IScope scope) {
+    this.ownerScope = scope;
+  }
+
+  @Override
+  @NotAstProperty
+  public boolean hasScope() {
+    return ownerScope!=null;
+  }
+
   public List<Expression> splitByComma() {
     return Collections.singletonList(this);
   }
diff --git a/src/main/java/com/github/sommeri/less4j/core/ast/IScopeAware.java b/src/main/java/com/github/sommeri/less4j/core/ast/IScopeAware.java
new file mode 100644
index 00000000..b447da1e
--- /dev/null
+++ b/src/main/java/com/github/sommeri/less4j/core/ast/IScopeAware.java
@@ -0,0 +1,24 @@
+package com.github.sommeri.less4j.core.ast;
+
+import com.github.sommeri.less4j.core.ast.annotations.NotAstProperty;
+import com.github.sommeri.less4j.core.compiler.scopes.IScope;
+
+/**
+ * Contains scope associated with the node. It would be much more cleaner if 
+ * the solution would keep ast completely independent from scope. That being said,
+ * I did not found such clean solution that would not be also fragile or too 
+ * complicated or required too much boiler plate like code. 
+ *
+ */
+public interface IScopeAware {
+	
+  @NotAstProperty
+	IScope getScope();
+
+  @NotAstProperty
+	void setScope(IScope scope);
+
+  @NotAstProperty
+	boolean hasScope();
+	
+}
diff --git a/src/main/java/com/github/sommeri/less4j/core/ast/ListExpression.java b/src/main/java/com/github/sommeri/less4j/core/ast/ListExpression.java
index 909085b5..2443cbd4 100644
--- a/src/main/java/com/github/sommeri/less4j/core/ast/ListExpression.java
+++ b/src/main/java/com/github/sommeri/less4j/core/ast/ListExpression.java
@@ -6,6 +6,7 @@
 
 import com.github.sommeri.less4j.core.ast.ListExpressionOperator.Operator;
 import com.github.sommeri.less4j.core.ast.annotations.NotAstProperty;
+import com.github.sommeri.less4j.core.compiler.scopes.IScope;
 import com.github.sommeri.less4j.core.parser.HiddenTokenAwareTree;
 import com.github.sommeri.less4j.utils.ArraysUtils;
 
@@ -20,6 +21,11 @@ public ListExpression(HiddenTokenAwareTree token, List<Expression> expressions,
     this.operator = operator;
   }
 
+  public ListExpression(HiddenTokenAwareTree token, List<Expression> expressions, ListExpressionOperator operator, IScope scope) {
+    this(token, expressions, operator);
+    setScope(scope);
+  }
+
   public ListExpressionOperator getOperator() {
     return operator;
   }
diff --git a/src/main/java/com/github/sommeri/less4j/core/compiler/scopes/BasicScope.java b/src/main/java/com/github/sommeri/less4j/core/compiler/scopes/BasicScope.java
index 595c7865..f0986926 100644
--- a/src/main/java/com/github/sommeri/less4j/core/compiler/scopes/BasicScope.java
+++ b/src/main/java/com/github/sommeri/less4j/core/compiler/scopes/BasicScope.java
@@ -20,13 +20,13 @@ public IScope firstChild() {
   public Expression getValue(Variable variable) {
     return getValue(variable.getName());
   }
-  
+
   public Expression getValue(String name) {
     Expression value = getLocalValue(name);
-    
+
     if (value == null && hasParent())
       value = getParent().getValue(name);
-    
+
     return value;
   }
 
@@ -62,7 +62,6 @@ public boolean seesLocalDataOf(IScope otherScope) {
     return getParent().seesLocalDataOf(otherScope);
   }
 
-
   public IScope getRootScope() {
     if (!hasParent())
       return this;
@@ -119,7 +118,13 @@ public String toFullName() {
 
   private String toSimpleName() {
     List<String> names = getNames();
-    return "" + getType() + names;
+    if (names!=null && !names.isEmpty())
+      return getType() + names;
+    
+    if (ScopeFactory.DEFAULT!=getType())
+      return getType() + "[" + getOwner().toString() + "]";
+    
+    return getType();
   }
 
   public String toLongString() {
diff --git a/src/main/java/com/github/sommeri/less4j/core/compiler/scopes/IteratedScope.java b/src/main/java/com/github/sommeri/less4j/core/compiler/scopes/IteratedScope.java
index e622fd2f..baeefbb9 100644
--- a/src/main/java/com/github/sommeri/less4j/core/compiler/scopes/IteratedScope.java
+++ b/src/main/java/com/github/sommeri/less4j/core/compiler/scopes/IteratedScope.java
@@ -3,6 +3,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 
+import com.github.sommeri.less4j.core.problems.BugHappened;
 
 public class IteratedScope {
 
@@ -24,6 +25,8 @@ public IteratedScope getNextChild() {
     do {
       if (childsIterator.hasNext())
         child = childsIterator.next();
+      else 
+        throw new BugHappened("Child scope was expected but missing", getScope().getOwner());
     } while (!child.isPresentInAst());
     
     return new IteratedScope(child);