diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexCPPBindingResolutionBugs.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexCPPBindingResolutionBugs.java
index 38eb0c788e7..10a0021dea4 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexCPPBindingResolutionBugs.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexCPPBindingResolutionBugs.java
@@ -1068,7 +1068,7 @@ public class IndexCPPBindingResolutionBugs extends IndexBindingResolutionTestBas
 	//      const int* q = p;
 	//		func(q);
 	//	}
-	public void _testOverloadedFunctionFromIndex_Bug256240() throws Exception {
+	public void testOverloadedFunctionFromIndex_Bug256240() throws Exception {
     	getBindingFromASTName("func(q", 4, ICPPFunction.class);
 	}
 
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPScope.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPScope.java
index fa826455c59..c5dbe1b4505 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPScope.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPScope.java
@@ -229,28 +229,34 @@ abstract public class CPPScope implements ICPPScope, ICPPASTInternalScope {
 	    final char[] c = name.getLookupKey();
 	    IBinding[] result = null;
 	    
-	    Object[] obj = null;
+	    Object obj = null;
 	    if (prefixLookup) {
 	    	Object[] keys = bindings != null ? bindings.keyArray() : new Object[0];
+	    	ObjectSet<Object> all= new ObjectSet<Object>(16);
 	    	for (int i = 0; i < keys.length; i++) {
 	    		final char[] key = (char[]) keys[i];
 	    		if (CharArrayUtils.equals(key, 0, c.length, c, true)) {
-	    			obj = ArrayUtil.append(obj, bindings.get(key));
+	    			obj= bindings.get(key);
+	    			if (obj instanceof ObjectSet<?>) {
+	    				all.addAll((ObjectSet<?>) obj);
+	    			} else if (obj != null) {
+	    				all.put(obj);
+	    			}
 	    		}
 	    	}
+	    	obj= all;
 	    } else {
-	    	obj = bindings != null ? new Object[] {bindings.get(c)} : null;
+	    	obj = bindings != null ? bindings.get(c) : null;
 	    }
 	    
-	    obj = ArrayUtil.trim(Object.class, obj);
-	    for (Object element : obj) {
-	        if (element instanceof ObjectSet<?>) {
-	        	ObjectSet<?> os= (ObjectSet<?>) element;
+	    if (obj != null) {
+	        if (obj instanceof ObjectSet<?>) {
+	        	ObjectSet<?> os= (ObjectSet<?>) obj;
         		for (int j = 0; j < os.size(); j++) {
         			result= addCandidate(os.keyAt(j), name, forceResolve, checkPointOfDecl, expandUsingDirectives, result);
         		}
 	        } else {
-	        	result = addCandidate(element, name, forceResolve, checkPointOfDecl, expandUsingDirectives, result);
+	        	result = addCandidate(obj, name, forceResolve, checkPointOfDecl, expandUsingDirectives, result);
 	        }
 	    }
 	    return (IBinding[]) ArrayUtil.trim(IBinding.class, result);
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
index 188f00f19a6..849d64789d5 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
@@ -1684,7 +1684,6 @@ public class CPPSemantics {
 	    IBinding type = null;
 	    IBinding obj  = null;
 	    IBinding temp = null;
-	    boolean fnsFromAST= false;
 	    
 	    Object[] items = (Object[]) data.foundItems;
 	    for (int i = 0; i < items.length && items[i] != null; i++) {
@@ -1738,22 +1737,9 @@ public class CPPSemantics {
 	        		if (!(temp instanceof IFunction))
 	        			continue;
 	        	}
-
-	        	IFunction function= (IFunction) temp;
 	        	if (fns == ObjectSet.EMPTY_SET)
 	        		fns = new ObjectSet<IFunction>(2);
-	        	if (isFromIndex(function)) {
-	        		// accept bindings from index only, in case we have none in the AST
-	        		if (!fnsFromAST) {
-	        			fns.put(function);
-	        		}
-	        	} else {
-	        		if (!fnsFromAST) {
-	        			fns.clear();
-	        			fnsFromAST= true;
-	        		}
-	        		fns.put(function);
-	        	}
+	        	fns.put((IFunction) temp);
 	        } else if (temp instanceof IType) {
 		        // specializations are selected during instantiation
 	        	if (temp instanceof ICPPClassTemplatePartialSpecialization) 
@@ -2083,6 +2069,16 @@ public class CPPSemantics {
 				} 
 			}
 			
+			// if we are ambiguous at this point prefer non-index bindings
+			if (hasBetter == hasWorse) {
+				final boolean bestIsFromIndex= isFromIndex(bestFn);
+				final boolean currIsFromIndex= isFromIndex(fn);
+				if (bestIsFromIndex != currIsFromIndex) {
+					hasBetter= bestIsFromIndex;
+					hasWorse= currIsFromIndex;
+				}
+			}
+								
 			// If function has a parameter match that is better than the current best,
 			// and another that is worse (or everything was just as good, neither better nor worse),
 			// then this is an ambiguity (unless we find something better than both later).
@@ -2232,6 +2228,19 @@ public class CPPSemantics {
         if (fns.length == 1)
             return fns[0];
         
+        IBinding oneFromAST= null;
+        for (IBinding fn : fns) {
+			if (!isFromIndex(fn)) {
+				if (oneFromAST != null) {
+					oneFromAST= null;
+					break;
+				}
+				oneFromAST= fn;
+			}
+		}
+        if (oneFromAST != null)
+        	return oneFromAST;
+        
         if (data.forAssociatedScopes) {
             return new CPPCompositeBinding(fns);
         }
@@ -2263,7 +2272,11 @@ public class CPPSemantics {
                 }
                 if (type.isSameType(ft)) {
                     if (result != null) {
-                        return new ProblemBinding(data.astName, IProblemBinding.SEMANTIC_AMBIGUOUS_LOOKUP);
+                    	boolean fromIndex= isFromIndex(fn);
+                    	if (isFromIndex(result) == fromIndex)
+                    		return new ProblemBinding(data.astName, IProblemBinding.SEMANTIC_AMBIGUOUS_LOOKUP);
+                    	if (!fromIndex)
+                    		result= fn;
                     }
                     result = fn;
                 }