diff --git a/proto/col_nullable.go b/proto/col_nullable.go
index e8e291e3..516245f0 100644
--- a/proto/col_nullable.go
+++ b/proto/col_nullable.go
@@ -35,7 +35,7 @@ func Null[T any]() Nullable[T] {
 func (n Nullable[T]) IsSet() bool { return n.Set }
 
 func (n Nullable[T]) Or(v T) T {
-	if n.Set {
+	if !n.Set {
 		return v
 	}
 	return n.Value
diff --git a/proto/col_nullable_test.go b/proto/col_nullable_test.go
index 037fe240..6332d8e4 100644
--- a/proto/col_nullable_test.go
+++ b/proto/col_nullable_test.go
@@ -11,6 +11,11 @@ import (
 	"github.com/ClickHouse/ch-go/internal/gold"
 )
 
+func TestNullable(t *testing.T) {
+	require.Equal(t, Null[string]().Or("foo"), "foo")
+	require.Equal(t, NewNullable("bar").Or("foo"), "bar")
+}
+
 func TestColNullable_EncodeColumn(t *testing.T) {
 	const rows = 10
 	data := new(ColStr).Nullable()