diff --git a/dbms/include/DB/DataTypes/DataTypeNull.h b/dbms/include/DB/DataTypes/DataTypeNull.h
index 52bba507715..e811781a026 100644
--- a/dbms/include/DB/DataTypes/DataTypeNull.h
+++ b/dbms/include/DB/DataTypes/DataTypeNull.h
@@ -14,8 +14,6 @@ public:
 public:
 	std::string getName() const override;
 	bool isNull() const override;
-	bool isNumeric() const override;
-	bool behavesAsNumber() const override;
 	DataTypePtr clone() const override;
 	void serializeBinary(const IColumn & column, WriteBuffer & ostr, size_t offset = 0, size_t limit = 0) const override;
 	void deserializeBinary(IColumn & column, ReadBuffer & istr, size_t limit, double avg_value_size_hint) const override;
diff --git a/dbms/include/DB/IO/WriteHelpers.h b/dbms/include/DB/IO/WriteHelpers.h
index ec1376c313f..47eff1928d2 100644
--- a/dbms/include/DB/IO/WriteHelpers.h
+++ b/dbms/include/DB/IO/WriteHelpers.h
@@ -804,4 +804,12 @@ inline String toString(const T & x)
 	return res;
 }
 
+/// Write a specified number of times a given value into a write buffer.
+template <typename T>
+inline void writeBinary(const T & x, size_t count, WriteBuffer & buf)
+{
+	for (size_t i = 0; i < count; ++i)
+		writeBinary(x, buf);
+}
+
 }
diff --git a/dbms/src/DataTypes/DataTypeNull.cpp b/dbms/src/DataTypes/DataTypeNull.cpp
index b1d81ceec8b..b196ec566d8 100644
--- a/dbms/src/DataTypes/DataTypeNull.cpp
+++ b/dbms/src/DataTypes/DataTypeNull.cpp
@@ -26,16 +26,6 @@ bool DataTypeNull::isNull() const
 	return true;
 }
 
-bool DataTypeNull::isNumeric() const
-{
-	return true;
-}
-
-bool DataTypeNull::behavesAsNumber() const
-{
-	return true;
-}
-
 DataTypePtr DataTypeNull::clone() const
 {
 	return std::make_shared<DataTypeNull>();
@@ -45,28 +35,19 @@ void DataTypeNull::serializeBinary(const IColumn & column, WriteBuffer & ostr, s
 {
 	size_t size = column.size();
 
-	if ((limit == 0) || (offset + limit) > size)
+	if ((limit == 0) || ((offset + limit) > size))
 		limit = size - offset;
 
-	UInt8 x = 0 ;
-	for (size_t i = 0; i < limit; ++i)
-		ostr.write(reinterpret_cast<const char *>(&x), sizeof(UInt8) * 1);
+	UInt8 x = 0;
+	writeBinary(x, limit, ostr);
 }
 
 void DataTypeNull::deserializeBinary(IColumn & column, ReadBuffer & istr, size_t limit, double avg_value_size_hint) const
 {
-	ColumnNull * col = typeid_cast<ColumnNull *>(&column);
-	if (col == nullptr)
-		throw Exception{"Discrepancy between data type and column type", ErrorCodes::LOGICAL_ERROR};
+	ColumnNull & null_col = static_cast<ColumnNull &>(column);
 
-	ColumnNull & col_ref = *col;
-
-	UInt8 x;
-	for (size_t i = 0; i < limit; ++i)
-	{
-		istr.readBig(reinterpret_cast<char *>(&x), sizeof(UInt8) * 1);
-		col_ref.insertDefault();
-	}
+	istr.ignore(sizeof(UInt8) * limit);
+	null_col.insertRangeFrom(ColumnNull{0, Null()}, 0, limit);
 }
 
 void DataTypeNull::serializeBinary(const Field & field, WriteBuffer & ostr) const
diff --git a/dbms/src/Functions/Conditional/ArgsInfo.cpp b/dbms/src/Functions/Conditional/ArgsInfo.cpp
index 4e7a1707784..71a8b29753c 100644
--- a/dbms/src/Functions/Conditional/ArgsInfo.cpp
+++ b/dbms/src/Functions/Conditional/ArgsInfo.cpp
@@ -203,7 +203,7 @@ bool hasArithmeticBranches(const DataTypes & args)
 
 	auto check = [&](size_t i)
 	{
-		return args[i]->behavesAsNumber();
+		return args[i]->behavesAsNumber() || args[i]->isNull();
 	};
 
 	for (size_t i = firstThen(); i < else_arg; i = nextThen(i))