diff --git a/src/AggregateFunctions/AggregateFunctionDistinct.h b/src/AggregateFunctions/AggregateFunctionDistinct.h
index 160e113d23b..bab78aa88bf 100644
--- a/src/AggregateFunctions/AggregateFunctionDistinct.h
+++ b/src/AggregateFunctions/AggregateFunctionDistinct.h
@@ -11,24 +11,35 @@
 namespace DB
 {
 
-namespace ErrorCodes
-{
+namespace ErrorCodes {
     extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
 }
 
+struct AggregateFunctionDistinctData {
+    using Key = UInt128;
+
+    HashSet<
+        Key,
+        UInt128TrivialHash,
+        HashTableGrower<3>,
+        HashTableAllocatorWithStackMemory<sizeof(Key) * (1 << 3)>
+    > data;
+    std::mutex mutex;
+
+    bool ALWAYS_INLINE TryToInsert(const Key& key) {
+        std::lock_guard lock(mutex);
+        return data.insert(key).second;
+    }
+};
+
 /** Adaptor for aggregate functions.
   * Adding -Distinct suffix to aggregate function
 **/
 
 class AggregateFunctionDistinct final : public IAggregateFunctionHelper<AggregateFunctionDistinct> {
 private:
-    mutable std::mutex mutex;
     AggregateFunctionPtr nested_func;
-    mutable HashSet<
-    UInt128,
-    UInt128TrivialHash,
-    HashTableGrower<3>,
-    HashTableAllocatorWithStackMemory<sizeof(UInt128) * (1 << 3)>> storage;
+    mutable AggregateFunctionDistinctData storage;
 
 public:
     AggregateFunctionDistinct(AggregateFunctionPtr nested, const DataTypes & arguments)
@@ -71,17 +82,14 @@ public:
     }
 
     void add(AggregateDataPtr place, const IColumn ** columns, size_t row_num, Arena * arena) const override {
-        UInt128 key;
         SipHash hash;
         columns[0]->updateHashWithValue(row_num, hash);
+
+        UInt128 key;
         hash.get128(key.low, key.high);
-        {
-            std::lock_guard lock(mutex);
-            if (!storage.insert(key).second) {
-                return;
-            }
-        }
-        nested_func->add(place, columns, row_num, arena);
+
+        if (storage.TryToInsert(key))
+            nested_func->add(place, columns, row_num, arena);
     }
 
     void merge(AggregateDataPtr place, ConstAggregateDataPtr rhs, Arena * arena) const override {