diff --git a/src/ag-db.c b/src/ag-db.c
index 42f0b19..7cf9422 100644
--- a/src/ag-db.c
+++ b/src/ag-db.c
@@ -17,6 +17,8 @@ typedef struct _AgDbPrivate {
     GdaConnection *conn;
 } AgDbPrivate;
 
+G_DEFINE_QUARK(ag_db_error_quark, ag_db_error);
+
 G_DEFINE_TYPE_WITH_PRIVATE(AgDb, ag_db, G_TYPE_OBJECT);
 
 static void
diff --git a/src/ag-db.h b/src/ag-db.h
index 3ac3447..104ad3b 100644
--- a/src/ag-db.h
+++ b/src/ag-db.h
@@ -49,6 +49,10 @@ typedef struct _AgDbSave {
     gchar *note;
 } AgDbSave;
 
+typedef enum {
+    AG_DB_ERROR_NO_CHART
+} AgDbError;
+
 GType ag_db_get_type(void) G_GNUC_CONST;
 
 AgDb *ag_db_get(void);
@@ -62,6 +66,9 @@ gboolean ag_db_save_chart(AgDb      *db,
 
 GList *ag_db_get_chart_list(AgDb *db, GError **err);
 
+#define AG_DB_ERROR (ag_db_error_quark())
+GQuark ag_db_error_quark(void);
+
 G_END_DECLS
 
 #endif /* __AG_DB_H__ */