diff --git a/types.go b/types.go
index ca16199..80f5259 100644
--- a/types.go
+++ b/types.go
@@ -12,6 +12,36 @@ import (
 	"github.com/lib/pq"
 )
 
+type NullBool struct {
+	sql.NullBool
+}
+
+func (b *NullBool) MarshalJSON() ([]byte, error) {
+	if !b.Valid {
+		return []byte("null"), nil
+	}
+	return json.Marshal(b.Bool)
+}
+
+func (n *NullBool) UnmarshalJSON(b []byte) error {
+	if bytes.Equal(b, []byte("null")) {
+		n.Bool = false
+		n.Valid = false
+		return nil
+	}
+	var x interface{}
+	var err error
+	json.Unmarshal(b, &x)
+	switch x.(type) {
+	case bool:
+		err = json.Unmarshal(b, &n.Bool)
+	case map[string]interface{}:
+		err = json.Unmarshal(b, &n.NullBool)
+	}
+	n.Valid = true
+	return err
+}
+
 type NullString struct {
 	sql.NullString
 }