diff --git a/src/Interpreters/ActionsDAG.cpp b/src/Interpreters/ActionsDAG.cpp
index 8bc430ee825..5f1398fed39 100644
--- a/src/Interpreters/ActionsDAG.cpp
+++ b/src/Interpreters/ActionsDAG.cpp
@@ -2260,32 +2260,4 @@ ActionsDAGPtr ActionsDAG::buildFilterActionsDAG(
     return result_dag;
 }
 
-const ActionsDAG::Node * ActionsDAG::getOriginalNodeForOutputAlias(const String & output_name)
-{
-    /// find alias in output
-    const Node * output_alias = nullptr;
-    for (const auto * node : outputs)
-    {
-        if (node->result_name == output_name && node->type == ActionsDAG::ActionType::ALIAS)
-        {
-            output_alias = node;
-            break;
-        }
-    }
-    if (!output_alias)
-        return nullptr;
-
-    /// find original(non alias) node it refers to
-    const Node * node = output_alias;
-    while (node && node->type == ActionsDAG::ActionType::ALIAS)
-    {
-        chassert(!node->children.empty());
-        node = node->children.front();
-    }
-    if (node->type != ActionsDAG::ActionType::INPUT)
-        return nullptr;
-
-    return node;
-}
-
 }
diff --git a/src/Interpreters/ActionsDAG.h b/src/Interpreters/ActionsDAG.h
index a1d57db71d5..40bc76fe057 100644
--- a/src/Interpreters/ActionsDAG.h
+++ b/src/Interpreters/ActionsDAG.h
@@ -347,9 +347,6 @@ public:
         const std::unordered_map<std::string, ColumnWithTypeAndName> & node_name_to_input_node_column,
         const ContextPtr & context);
 
-    /// Return original node (input) for alias in output if exists
-    const Node * getOriginalNodeForOutputAlias(const String & output_name);
-
 private:
     NodeRawConstPtrs getParents(const Node * target) const;
 
diff --git a/src/Processors/QueryPlan/Optimizations/removeRedundantDistinct.cpp b/src/Processors/QueryPlan/Optimizations/removeRedundantDistinct.cpp
index aa235e9e8af..1b012d81f82 100644
--- a/src/Processors/QueryPlan/Optimizations/removeRedundantDistinct.cpp
+++ b/src/Processors/QueryPlan/Optimizations/removeRedundantDistinct.cpp
@@ -37,6 +37,34 @@ namespace
         return non_const_columns;
     }
 
+    const ActionsDAG::Node * getOriginalNodeForOutputAlias(const ActionsDAGPtr & actions, const String & output_name)
+    {
+        /// find alias in output
+        const ActionsDAG::Node * output_alias = nullptr;
+        for (const auto * node : actions->getOutputs())
+        {
+            if (node->result_name == output_name && node->type == ActionsDAG::ActionType::ALIAS)
+            {
+                output_alias = node;
+                break;
+            }
+        }
+        if (!output_alias)
+            return nullptr;
+
+        /// find original(non alias) node it refers to
+        const ActionsDAG::Node * node = output_alias;
+        while (node && node->type == ActionsDAG::ActionType::ALIAS)
+        {
+            chassert(!node->children.empty());
+            node = node->children.front();
+        }
+        if (node->type != ActionsDAG::ActionType::INPUT)
+            return nullptr;
+
+        return node;
+    }
+
     bool canRemoveDistinct(const QueryPlan::Node * distinct_node)
     {
         const DistinctStep * distinct_step = typeid_cast<DistinctStep *>(distinct_node->step.get());
@@ -98,7 +126,7 @@ namespace
             /// compare columns of two DISTINCTs
             for (const auto & column : distinct_columns)
             {
-                const auto * alias_node = path_actions->getOriginalNodeForOutputAlias(String(column));
+                const auto * alias_node = getOriginalNodeForOutputAlias(path_actions, String(column));
                 if (!alias_node)
                     return false;
 
@@ -129,7 +157,7 @@ size_t tryRemoveRedundantDistinct(QueryPlan::Node * parent_node, QueryPlan::Node
     for (const auto * node : parent_node->children)
     {
         /// check if it is distinct node
-        if (typeid_cast<const DistinctStep *>(node->step.get()))
+        if (typeid_cast<const DistinctStep *>(node->step.get()) == nullptr)
             continue;
 
         if (canRemoveDistinct(node))