diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/prefix/BasicCompletionTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/prefix/BasicCompletionTest.java
index a93c278b44c..74c3044f17d 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/prefix/BasicCompletionTest.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/prefix/BasicCompletionTest.java
@@ -337,4 +337,25 @@ public class BasicCompletionTest extends CompletionTestBase {
 		String[] expected= {"fooBar", "foo_bar"};
 		checkCompletion(code, false, expected);
 	}
+	
+	//	void someFunction() {
+	//	    int abc[5];
+	//	    sizeof(ab
+	public void testCompletionInSizeof340664() throws Exception {
+		String code = getAboveComment();
+		String[] expected= {"abc"};
+		checkCompletion(code, false, expected);
+		checkCompletion(code, true, expected);
+	}
+	
+	//	typedef int abc;
+	//	struct X {
+	//	  X(ab
+	public void testCompletionInParamlistOfCtor_338949() throws Exception {
+		String code = getAboveComment();
+		String[] expected= {"abc"};
+		checkCompletion(code, false, expected);
+		checkCompletion(code, true, expected);
+	}
+
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTQueries.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTQueries.java
index 74f602a2cfe..81679d19643 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTQueries.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTQueries.java
@@ -103,6 +103,9 @@ public class ASTQueries {
 	 * Searches for the innermost declarator that contributes the the type declared.
 	 */
 	public static IASTDeclarator findTypeRelevantDeclarator(IASTDeclarator declarator) {
+		if (declarator == null)
+			return null;
+		
 		IASTDeclarator result= findInnermostDeclarator(declarator);
 		while (result.getPointerOperators().length == 0 
 				&& !(result instanceof IASTFieldDeclarator)
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPClassScope.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPClassScope.java
index 1ed91896e50..e2b956327dd 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPClassScope.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPClassScope.java
@@ -521,7 +521,7 @@ class ImplicitsAnalysis {
 	private static boolean paramHasTypeReferenceToTheAssociatedClassType(IASTParameterDeclaration dec, String name) {
 		boolean result= false;
 		IASTDeclarator pdtor= ASTQueries.findTypeRelevantDeclarator(dec.getDeclarator());
-		if (pdtor.getPointerOperators().length == 1 &&
+		if (pdtor != null && pdtor.getPointerOperators().length == 1 &&
 				pdtor.getPointerOperators()[0] instanceof ICPPASTReferenceOperator &&
 				pdtor.getParent() == dec &&
 				dec.getDeclSpecifier() instanceof ICPPASTNamedTypeSpecifier) {