diff --git a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/ElementValue.java b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/ElementValue.java
index 4f099d3..d0d6c3c 100644
--- a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/ElementValue.java
+++ b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/ElementValue.java
@@ -141,7 +141,8 @@
 				if (!selection.isEmpty()) {
 					if (selection.size() == 1) {
 						final IRMember selected = selection.get(0);
-						if ("prototype".equals(selected.getName())
+						if (IRLocalType.PROTOTYPE_PROPERTY.equals(selected
+								.getName())
 								&& selected instanceof IRProperty) {
 							if (t != null) {
 								return new PrototypePropertyValue(
diff --git a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java
index 2585112..949ffd6 100644
--- a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java
+++ b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java
@@ -123,6 +123,7 @@
 import org.eclipse.dltk.javascript.typeinfo.IRLocalType;
 import org.eclipse.dltk.javascript.typeinfo.IRMapType;
 import org.eclipse.dltk.javascript.typeinfo.IRMethod;
+import org.eclipse.dltk.javascript.typeinfo.IRProperty;
 import org.eclipse.dltk.javascript.typeinfo.IRRecordMember;
 import org.eclipse.dltk.javascript.typeinfo.IRSimpleType;
 import org.eclipse.dltk.javascript.typeinfo.IRType;
@@ -448,6 +449,21 @@
 									&& !declaredType.isJavaScriptObject()) {
 								// skip assignment
 								return right;
+							} else {
+								// if the assignment is done on the prototype property
+								// then make sure it is not IRProperty (the one from Object itself)
+								// replace that with a AnonymousValue
+								Object attribute = leftParent
+										.getAttribute(IReferenceAttributes.ELEMENT);
+								if (attribute instanceof IRProperty
+										&& ((IRProperty) attribute).getName()
+												.equals(IRLocalType.PROTOTYPE_PROPERTY)) {
+									leftParent.getParent()
+											.createChild(
+													IRLocalType.PROTOTYPE_PROPERTY)
+											.setValue(new AnonymousValue());
+								}
+
 							}
 						}
 					}
@@ -873,7 +889,8 @@
 					.getExtendsType());
 			thisValue.setDeclaredType(thisType);
 			if (thisType instanceof IRLocalType) {
-				IValueReference prototype = result.createChild("prototype");
+				IValueReference prototype = result
+						.createChild(IRLocalType.PROTOTYPE_PROPERTY);
 				prototype.setDeclaredType(context.getType(ITypeNames.OBJECT)
 						.toRType(context));
 				Set<String> directChildren = ((IRLocalType) thisType)
diff --git a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/javascript/typeinfo/IRLocalType.java b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/javascript/typeinfo/IRLocalType.java
index 5137b30..5bd242d 100644
--- a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/javascript/typeinfo/IRLocalType.java
+++ b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/javascript/typeinfo/IRLocalType.java
@@ -21,6 +21,8 @@
  * @author jcompagner
  */
 public interface IRLocalType extends IRType, IRTypeExtension {
+	public static final String PROTOTYPE_PROPERTY = "prototype";
+
 	public IValueReference getValue();
 
 	@Nullable
diff --git a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/javascript/typeinfo/RLocalType.java b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/javascript/typeinfo/RLocalType.java
index bace625..c81c57e 100644
--- a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/javascript/typeinfo/RLocalType.java
+++ b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/javascript/typeinfo/RLocalType.java
@@ -48,15 +48,7 @@
 	}
 
 	public IValueReference getDirectChild(String name) {
-		final IValueReference value = getValue();
-		if (value.getDirectChildren(IValue.NO_LOCAL_TYPES).contains(name)) {
-			return value.getChild(name);
-		} else {
-			JSTypeSet declaredTypes = getValue().getDeclaredTypes();
-			HashSet<IRType> set = new HashSet<IRType>();
-			set.add(this);
-			return getChildFromDeclaredTypes(name, declaredTypes, set);
-		}
+		return getChild(this, name, new HashSet<IRType>());
 	}
 
 	/**
@@ -67,38 +59,64 @@
 	private IValueReference getChildFromDeclaredTypes(String name,
 			JSTypeSet declaredTypes, HashSet<IRType> set) {
 		for (IRType irType : declaredTypes) {
-			if (irType instanceof RLocalType && set.add(irType)) {
-				IValueReference declaredValue = ((RLocalType) irType)
-						.getValue();
-				if (declaredValue.getDirectChildren(IValue.NO_LOCAL_TYPES)
-						.contains(name)) {
-					return declaredValue.getChild(name);
-				}
-				IValueReference fromChild = getChildFromDeclaredTypes(name,
-						declaredValue.getDeclaredTypes(), set);
-				if (fromChild != null)
-					return fromChild;
+			if (irType instanceof RLocalType) {
+				IValueReference child = getChild((RLocalType) irType, name, set);
+				if (child != null)
+					return child;
 			}
 		}
 		return null;
 	}
 
+	private IValueReference getChild(RLocalType irType, String name,
+			HashSet<IRType> set) {
+		if (set.add(irType)) {
+			IValueReference declaredValue = irType.getValue();
+			if (declaredValue.getDirectChildren(IValue.NO_LOCAL_TYPES)
+					.contains(name)) {
+				return declaredValue.getChild(name);
+			}
+			IValueReference fromChild = getChildFromDeclaredTypes(name,
+					declaredValue.getDeclaredTypes(), set);
+			if (fromChild == null) {
+				IValueReference prototype = irType.functionValue
+						.getChild(PROTOTYPE_PROPERTY);
+				if (prototype.getDirectChildren().contains(name)) {
+					return prototype.getChild(name);
+				}
+			}
+			return fromChild;
+		}
+		return null;
+	}
+
 	public Set<String> getDirectChildren() {
-		Set<String> children = getValue().getDirectChildren(
-				IValue.NO_LOCAL_TYPES);
-		JSTypeSet declaredTypes = getValue().getDeclaredTypes();
-		HashSet<IRType> set = new HashSet<IRType>();
-		set.add(this);
-		fillDeclaredLocalTypesChildren(children, declaredTypes, set);
+		Set<String> children = new HashSet<String>();
+		fillChildren(this, children, new HashSet<IRType>());
 		return children;
 	}
 
+	private static void fillChildren(RLocalType rLocalType,
+			Set<String> children,
+			HashSet<IRType> set) {
+		if (set.add(rLocalType)) {
+			IValueReference value = rLocalType.getValue();
+			children.addAll(value.getDirectChildren(
+					IValue.NO_LOCAL_TYPES));
+			IValueReference prototype = rLocalType.functionValue
+					.getChild(PROTOTYPE_PROPERTY);
+			children.addAll(prototype.getDirectChildren());
+			fillDeclaredLocalTypesChildren(children, value
+					.getDeclaredTypes(), set);
+		}
+	}
+
 	/**
 	 * @param children
 	 * @param declaredTypes
 	 * @param set
 	 */
-	private void fillDeclaredLocalTypesChildren(Set<String> children,
+	private static void fillDeclaredLocalTypesChildren(Set<String> children,
 			JSTypeSet declaredTypes, HashSet<IRType> set) {
 		for (IRType irType : declaredTypes) {
 			if (irType instanceof RLocalType && set.add(irType)) {
diff --git a/tests/org.eclipse.dltk.javascript.core.tests/src/org/eclipse/dltk/javascript/core/tests/contentassist/CodeCompletion.java b/tests/org.eclipse.dltk.javascript.core.tests/src/org/eclipse/dltk/javascript/core/tests/contentassist/CodeCompletion.java
index 29bfc1e..63030a4 100644
--- a/tests/org.eclipse.dltk.javascript.core.tests/src/org/eclipse/dltk/javascript/core/tests/contentassist/CodeCompletion.java
+++ b/tests/org.eclipse.dltk.javascript.core.tests/src/org/eclipse/dltk/javascript/core/tests/contentassist/CodeCompletion.java
@@ -949,4 +949,42 @@
 		}
 		assertEquals(true, found);
 	}
+	
+	public void testPrototypeFunctionWith2Extends() {
+		final StringList code = new StringList();
+		code.add("function A() {}");
+		code.add("A.prototype.afunction = function(){ }");
+		code.add("/**");
+		code.add(" * @extends {A}");
+		code.add(" */");
+		code.add("function B() {}");
+		code.add("B.prototype = new A();");
+		code.add("B.prototype.bfunction = function(){ }");
+		code.add("/**");
+		code.add(" * @extends {B}");
+		code.add(" */");
+		code.add("function C() {}");
+		code.add("C.prototype = new B();");
+		code.add("C.prototype.testDirectAssignment = function(){ }");
+		code.add("var x = new C();");
+		code.add("x.");
+		final IModuleSource module = new TestModule(code.toString());
+		final List<CompletionProposal> results = new ArrayList<CompletionProposal>();
+		final ICompletionEngine completionEngine = createEngine(results,
+				JSCompletionEngine.OPTION_KEYWORDS);
+		completionEngine.complete(module, lastPositionInFile(".", module), 0);
+		int found = 0;
+		for (CompletionProposal completionProposal : results) {
+			if (completionProposal.getName().equals("testDirectAssignment")) {
+				found++;
+			}
+			if (completionProposal.getName().equals("bfunction")) {
+				found++;
+			}
+			if (completionProposal.getName().equals("afunction")) {
+				found++;
+			}
+		}
+		assertEquals(3, found);
+	}
 }
diff --git a/tests/org.eclipse.dltk.javascript.core.tests/src/org/eclipse/dltk/javascript/core/tests/validation/TypeInfoValidationTests.java b/tests/org.eclipse.dltk.javascript.core.tests/src/org/eclipse/dltk/javascript/core/tests/validation/TypeInfoValidationTests.java
index 1836472..329cd39 100644
--- a/tests/org.eclipse.dltk.javascript.core.tests/src/org/eclipse/dltk/javascript/core/tests/validation/TypeInfoValidationTests.java
+++ b/tests/org.eclipse.dltk.javascript.core.tests/src/org/eclipse/dltk/javascript/core/tests/validation/TypeInfoValidationTests.java
@@ -3644,5 +3644,53 @@
 		final List<IProblem> problems = validate(code.toString());
 		assertEquals(problems.toString(), 0, problems.size());
 	}
+	
+	public void testPrototypeFunction() {
+		final StringList code = new StringList();
+		code.add("function A() {}");
+		code.add("A.prototype.testDirectAssignment = function(){ }");
+		code.add("var x = new A();");
+		code.add("x.testDirectAssignment();");
+		final List<IProblem> problems = validate(code.toString());
+		assertEquals(problems.toString(), 0, problems.size());
+	}
 
+	public void testPrototypeFunctionWithExtends() {
+		final StringList code = new StringList();
+		code.add("function A() {}");
+		code.add("/**");
+		code.add(" * @extends {A}");
+		code.add(" */");
+		code.add("function B() {}");
+		code.add("B.prototype = new A();");
+		code.add("B.prototype.testDirectAssignment = function(){ }");
+		code.add("var x = new B();");
+		code.add("x.testDirectAssignment();");
+		final List<IProblem> problems = validate(code.toString());
+		assertEquals(problems.toString(), 0, problems.size());
+	}
+	
+	public void testPrototypeFunctionWith2Extends() {
+		final StringList code = new StringList();
+		code.add("function A() {}");
+		code.add("A.prototype.afunction = function(){ }");
+		code.add("/**");
+		code.add(" * @extends {A}");
+		code.add(" */");
+		code.add("function B() {}");
+		code.add("B.prototype = new A();");
+		code.add("B.prototype.bfunction = function(){ }");
+		code.add("/**");
+		code.add(" * @extends {B}");
+		code.add(" */");
+		code.add("function C() {}");
+		code.add("C.prototype = new B();");
+		code.add("C.prototype.testDirectAssignment = function(){ }");
+		code.add("var x = new C();");
+		code.add("x.testDirectAssignment();");
+		code.add("x.bfunction();");
+		code.add("x.afunction();");
+		final List<IProblem> problems = validate(code.toString());
+		assertEquals(problems.toString(), 0, problems.size());
+	}
 }