diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2TemplateTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2TemplateTests.java
index 78245d1ce22..46283bd5219 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2TemplateTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2TemplateTests.java
@@ -9292,6 +9292,23 @@ public class AST2TemplateTests extends AST2TestBase {
 		ICPPVariable waldo = helper.assertNonProblem("waldo");
 		assertConstantValue(0, waldo);
 	}
+	
+	//	template <typename T>
+	//	struct traits {
+	//	    static constexpr int Flags = 1;
+	//	};
+	//	
+	//	template <typename T>
+	//	struct S {
+	//	    static constexpr int a = traits<T>::Flags;
+	//	    static constexpr int b = a ? 42 : 0;
+	//	};
+	//
+	//	constexpr int waldo = S<int>::b;
+	public void testDependentConditionalExpression_506170() throws Exception {
+		BindingAssertionHelper helper = getAssertionHelper();
+		helper.assertVariableValue("waldo", 42);
+	}
 
 	//	template <typename>
 	//	struct C {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ValueFactory.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ValueFactory.java
index 672970714e2..3ef448f40c6 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ValueFactory.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ValueFactory.java
@@ -282,8 +282,10 @@ public class ValueFactory {
 		if (exp instanceof IASTConditionalExpression) {
 			IASTConditionalExpression cexpr= (IASTConditionalExpression) exp;
 			IValue v= evaluate(cexpr.getLogicalConditionExpression());
-			if (isInvalidValue(v) || v.numberValue() == null)
+			if (isInvalidValue(v))
 				return v;
+			if (isDeferredValue(v))
+				return null;  // the value will be computed using the evaluation
 			if (v.numberValue().longValue() == 0) {
 				return evaluate(cexpr.getNegativeResultExpression());
 			}