In the code below, IDEA displays a possible NPE warning for "((PsiVariable)element.getParent())". The "assert" QuickFix however doesn't work because element.getParent() could return a different value (null) for the second invocation. That's why the QuickFix doesn't fix anything public class Test { public void test(@NotNull PsiElement element) { if (checkSomething(element)) { // This doesn't remove the NPE warning: // assert ((PsiVariable)element.getParent()) != null; if (((PsiVariable)element.getParent()).getNameIdentifier() != null) { // ... } } } private boolean checkSomething(@NotNull PsiElement element) { return element.getParent() instanceof PsiVariable; } } #1 Offering the QuickFix here seems to be a bug because IDEA doesn't realize that the expression is potentially non-constant. (It does realize this for similar expressions without the type cast). #2 The QuickFix should actually be offered for any possible NPE-warning and automatically introduce a local variable for potentially non-constant expressions: PsiVariable psiVariable = ((PsiVariable)element.getParent()); assert psiVariable != null; if (psiVariable.getNameIdentifier() != null) { // ... }