diff --git a/src/Functions/FunctionsConversion.h b/src/Functions/FunctionsConversion.h
index c277997593c..362249b3b27 100644
--- a/src/Functions/FunctionsConversion.h
+++ b/src/Functions/FunctionsConversion.h
@@ -3470,7 +3470,7 @@ protected:
         if constexpr (internal)
             return type;
 
-        if (keep_nullable && arguments.front().type->isNullable())
+        if (keep_nullable && arguments.front().type->isNullable() && type->canBeInsideNullable())
             return makeNullable(type);
 
         return type;
diff --git a/tests/queries/0_stateless/00974_low_cardinality_cast.sql b/tests/queries/0_stateless/00974_low_cardinality_cast.sql
index e369a8c169e..b52c00513d3 100644
--- a/tests/queries/0_stateless/00974_low_cardinality_cast.sql
+++ b/tests/queries/0_stateless/00974_low_cardinality_cast.sql
@@ -1,3 +1,5 @@
+SET cast_keep_nullable = 0;
+
 SELECT CAST('Hello' AS LowCardinality(Nullable(String)));
 SELECT CAST(Null AS LowCardinality(Nullable(String)));
 SELECT CAST(CAST('Hello' AS LowCardinality(Nullable(String))) AS String);
diff --git a/tests/queries/0_stateless/01402_cast_nullable_string_to_enum.sql b/tests/queries/0_stateless/01402_cast_nullable_string_to_enum.sql
index aa8e8be6673..3b53e593095 100644
--- a/tests/queries/0_stateless/01402_cast_nullable_string_to_enum.sql
+++ b/tests/queries/0_stateless/01402_cast_nullable_string_to_enum.sql
@@ -1,3 +1,5 @@
+SET cast_keep_nullable = 0;
+
 -- https://github.com/ClickHouse/ClickHouse/issues/5818#issuecomment-619628445
 SELECT CAST(CAST(NULL AS Nullable(String)) AS Nullable(Enum8('Hello' = 1)));
 SELECT CAST(CAST(NULL AS Nullable(FixedString(1))) AS Nullable(Enum8('Hello' = 1)));
diff --git a/tests/queries/0_stateless/01536_fuzz_cast.sql b/tests/queries/0_stateless/01536_fuzz_cast.sql
index 436d76b5c4c..fb1303549b6 100644
--- a/tests/queries/0_stateless/01536_fuzz_cast.sql
+++ b/tests/queries/0_stateless/01536_fuzz_cast.sql
@@ -1 +1,2 @@
+SET cast_keep_nullable = 0;
 SELECT CAST(arrayJoin([NULL, '', '', NULL, '', NULL, '01.02.2017 03:04\005GMT', '', NULL, '01/02/2017 03:04:05 MSK01/02/\0017 03:04:05 MSK', '', NULL, '03/04/201903/04/201903/04/\001903/04/2019']), 'Enum8(\'a\' = 1, \'b\' = 2)') AS x; -- { serverError 349 }
diff --git a/tests/queries/0_stateless/01655_plan_optimizations.reference b/tests/queries/0_stateless/01655_plan_optimizations.reference
index 22f5a2e73e3..22876207862 100644
--- a/tests/queries/0_stateless/01655_plan_optimizations.reference
+++ b/tests/queries/0_stateless/01655_plan_optimizations.reference
@@ -56,7 +56,7 @@ Filter column: notEquals(y, 0)
 9	10
 > one condition of filter should be pushed down after aggregating, other condition is casted
 Filter column
-FUNCTION CAST(minus(s, 4) :: 1, UInt8 :: 3) -> and(notEquals(y, 0), minus(s, 4))
+FUNCTION _CAST(minus(s, 4) :: 1, UInt8 :: 3) -> and(notEquals(y, 0), minus(s, 4))
 Aggregating
 Filter column: notEquals(y, 0)
 0	1
diff --git a/tests/queries/0_stateless/01655_plan_optimizations.sh b/tests/queries/0_stateless/01655_plan_optimizations.sh
index 148e6157773..b835bae0e27 100755
--- a/tests/queries/0_stateless/01655_plan_optimizations.sh
+++ b/tests/queries/0_stateless/01655_plan_optimizations.sh
@@ -56,7 +56,7 @@ $CLICKHOUSE_CLIENT -q "
         select sum(x) as s, y from (select number as x, number + 1 as y from numbers(10)) group by y
     ) where y != 0 and s - 4
     settings enable_optimize_predicate_expression=0" |
-    grep -o "Aggregating\|Filter column\|Filter column: notEquals(y, 0)\|FUNCTION CAST(minus(s, 4) :: 1, UInt8 :: 3) -> and(notEquals(y, 0), minus(s, 4))"
+    grep -o "Aggregating\|Filter column\|Filter column: notEquals(y, 0)\|FUNCTION _CAST(minus(s, 4) :: 1, UInt8 :: 3) -> and(notEquals(y, 0), minus(s, 4))"
 $CLICKHOUSE_CLIENT -q "
     select s, y from (
         select sum(x) as s, y from (select number as x, number + 1 as y from numbers(10)) group by y
diff --git a/tests/queries/0_stateless/01720_join_implicit_cast.sql.j2 b/tests/queries/0_stateless/01720_join_implicit_cast.sql.j2
index f7760c38163..f2b13e9824b 100644
--- a/tests/queries/0_stateless/01720_join_implicit_cast.sql.j2
+++ b/tests/queries/0_stateless/01720_join_implicit_cast.sql.j2
@@ -48,8 +48,8 @@ SELECT any(toTypeName(a)) == 'Int32' AND any(toTypeName(b)) == 'Nullable(Int64)'
 SELECT any(toTypeName(a)) == 'Int32' AND any(toTypeName(b)) == 'Nullable(Int64)' FROM t_ab1 RIGHT JOIN t_ab2 USING (a, b);
 SELECT any(toTypeName(a)) == 'Int32' AND any(toTypeName(b)) == 'Nullable(Int64)' FROM t_ab1 INNER JOIN t_ab2 USING (a, b);
 
-SELECT * FROM ( SELECT a, b as "CAST(a, Int32)" FROM t_ab1 ) t_ab1 FULL JOIN t_ab2 ON (t_ab1.a == t_ab2.a); -- { serverError 44 }
-SELECT * FROM ( SELECT a, b as "CAST(a, Int32)" FROM t_ab1 ) t_ab1 FULL JOIN t_ab2 USING (a) FORMAT Null;
+SELECT * FROM ( SELECT a, b as "_CAST(a, Int32)" FROM t_ab1 ) t_ab1 FULL JOIN t_ab2 ON (t_ab1.a == t_ab2.a); -- { serverError 44 }
+SELECT * FROM ( SELECT a, b as "_CAST(a, Int32)" FROM t_ab1 ) t_ab1 FULL JOIN t_ab2 USING (a) FORMAT Null;
 
 {% endfor %}
 
diff --git a/tests/queries/0_stateless/01756_optimize_skip_unused_shards_rewrite_in.reference b/tests/queries/0_stateless/01756_optimize_skip_unused_shards_rewrite_in.reference
index 972f4c89bdf..66fbe8a5d1c 100644
--- a/tests/queries/0_stateless/01756_optimize_skip_unused_shards_rewrite_in.reference
+++ b/tests/queries/0_stateless/01756_optimize_skip_unused_shards_rewrite_in.reference
@@ -1,17 +1,17 @@
 (0, 2)
 0	0
 0	0
-WITH CAST(\'default\', \'Nullable(String)\') AS id_no SELECT one.dummy, ignore(id_no) FROM system.one WHERE dummy IN (0, 2)
-WITH CAST(\'default\', \'Nullable(String)\') AS id_no SELECT one.dummy, ignore(id_no) FROM system.one WHERE dummy IN (0, 2)
+WITH _CAST(\'default\', \'Nullable(String)\') AS id_no SELECT one.dummy, ignore(id_no) FROM system.one WHERE dummy IN (0, 2)
+WITH _CAST(\'default\', \'Nullable(String)\') AS id_no SELECT one.dummy, ignore(id_no) FROM system.one WHERE dummy IN (0, 2)
 optimize_skip_unused_shards_rewrite_in(0, 2)
 0	0
-WITH CAST(\'default\', \'Nullable(String)\') AS id_02 SELECT one.dummy, ignore(id_02) FROM system.one WHERE dummy IN tuple(0)
-WITH CAST(\'default\', \'Nullable(String)\') AS id_02 SELECT one.dummy, ignore(id_02) FROM system.one WHERE dummy IN tuple(2)
+WITH _CAST(\'default\', \'Nullable(String)\') AS id_02 SELECT one.dummy, ignore(id_02) FROM system.one WHERE dummy IN tuple(0)
+WITH _CAST(\'default\', \'Nullable(String)\') AS id_02 SELECT one.dummy, ignore(id_02) FROM system.one WHERE dummy IN tuple(2)
 optimize_skip_unused_shards_rewrite_in(2,)
-WITH CAST(\'default\', \'Nullable(String)\') AS id_2 SELECT one.dummy, ignore(id_2) FROM system.one WHERE dummy IN tuple(2)
+WITH _CAST(\'default\', \'Nullable(String)\') AS id_2 SELECT one.dummy, ignore(id_2) FROM system.one WHERE dummy IN tuple(2)
 optimize_skip_unused_shards_rewrite_in(0,)
 0	0
-WITH CAST(\'default\', \'Nullable(String)\') AS id_0 SELECT one.dummy, ignore(id_0) FROM system.one WHERE dummy IN tuple(0)
+WITH _CAST(\'default\', \'Nullable(String)\') AS id_0 SELECT one.dummy, ignore(id_0) FROM system.one WHERE dummy IN tuple(0)
 0
 0
 errors