diff --git a/Python/ast.c b/Python/ast.c
index 3381260..c7fd8bc 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -1878,10 +1878,14 @@
 	}
 	else if (TYPE(ch) == STAR) {
 	    vararg = ast_for_expr(c, CHILD(n, i+1));
+	    if (!vararg)
+	        return NULL;
 	    i++;
 	}
 	else if (TYPE(ch) == DOUBLESTAR) {
 	    kwarg = ast_for_expr(c, CHILD(n, i+1));
+	    if (!kwarg)
+	        return NULL;
 	    i++;
 	}
     }