diff --git a/src/common/expression/LabelAttributeExpression.h b/src/common/expression/LabelAttributeExpression.h
index d83a5af2c..9db7b4188 100644
--- a/src/common/expression/LabelAttributeExpression.h
+++ b/src/common/expression/LabelAttributeExpression.h
@@ -35,6 +35,7 @@ class LabelAttributeExpression final : public Expression {
 
     const Value& eval(ExpressionContext&) override {
         LOG(FATAL) << "LabelAttributeExpression has to be rewritten";
+        return Value::kNullBadData;
     }
 
     void accept(ExprVisitor *visitor) override;
diff --git a/src/common/expression/TextSearchExpression.h b/src/common/expression/TextSearchExpression.h
index 83814a720..21b28dcda 100644
--- a/src/common/expression/TextSearchExpression.h
+++ b/src/common/expression/TextSearchExpression.h
@@ -82,8 +82,6 @@ class TextSearchArgument final {
 };
 
 class TextSearchExpression : public Expression {
-    friend class Expression;
-
 public:
     TextSearchExpression(Kind kind, TextSearchArgument* arg)
         : Expression(kind) {
@@ -94,6 +92,7 @@ class TextSearchExpression : public Expression {
 
     const Value& eval(ExpressionContext&) override {
         LOG(FATAL) << "TextSearchExpression has to be rewritten";
+        return Value::kNullBadData;
     }
 
     void accept(ExprVisitor*) override {