diff --git a/src/Analyzer/FunctionSecretArgumentsFinderTreeNode.h b/src/Analyzer/FunctionSecretArgumentsFinderTreeNode.h
index 3c0e5974d16..8e8f56760e4 100644
--- a/src/Analyzer/FunctionSecretArgumentsFinderTreeNode.h
+++ b/src/Analyzer/FunctionSecretArgumentsFinderTreeNode.h
@@ -16,7 +16,12 @@ public:
     {
     public:
         explicit ArgumentTreeNode(const IQueryTreeNode * argument_) : argument(argument_) {}
-        std::unique_ptr<AbstractFunction> getFunction() const override { return std::make_unique<FunctionTreeNode>(*argument->as<FunctionNode>()); }
+        std::unique_ptr<AbstractFunction> getFunction() const override
+        {
+            if (const auto * f = argument->as<FunctionNode>())
+                return std::make_unique<FunctionTreeNode>(*f);
+            return nullptr;
+        }
         bool isIdentifier() const override { return argument->as<IdentifierNode>(); }
         bool tryGetString(String * res, bool allow_identifier = true) const override
         {
diff --git a/src/Parsers/FunctionSecretArgumentsFinderAST.h b/src/Parsers/FunctionSecretArgumentsFinderAST.h
index d2d7a63aff1..9430053d6a5 100644
--- a/src/Parsers/FunctionSecretArgumentsFinderAST.h
+++ b/src/Parsers/FunctionSecretArgumentsFinderAST.h
@@ -16,7 +16,12 @@ public:
         {
         public:
             explicit ArgumentAST(const IAST * argument_) : argument(argument_) {}
-            std::unique_ptr<AbstractFunction> getFunction() const override { return std::make_unique<FunctionAST>(*argument->as<ASTFunction>()); }
+            std::unique_ptr<AbstractFunction> getFunction() const override
+            {
+                if (const auto * f = argument->as<ASTFunction>())
+                    return std::make_unique<FunctionAST>(*f);
+                return nullptr;
+            }
             bool isIdentifier() const override { return argument->as<ASTIdentifier>(); }
             bool tryGetString(String * res, bool allow_identifier = true) const override
             {