diff --git a/main.c b/main.c
index 7401a75905643ab6143bf1196269eef6e51eb350..fed9f0bf37d2893e76e7a38b68719109570db144 100644
--- a/main.c
+++ b/main.c
@@ -215,28 +215,42 @@ static void
 config_db (AppData* appdata)
 {
 	gint ri = 0;
-	gboolean r = FALSE;
+	gboolean rb = FALSE;
 	static const char* SQLITE3_MEMORY_DB = ":memory:";
 	sqlite3* db = NULL;
 	gchar* sql = NULL;
 	ri = sqlite3_open (SQLITE3_MEMORY_DB, &db);
-	g_assert_cmpint (ri, ==, SQLITE_OK);
+	if (ri != SQLITE_OK) {
+		g_warning ("sqlite3_open :memory: db failed, query will not work.");
+		goto db_fail;
+	}
 	g_assert_nonnull (db);
 
 	/* TODO make db path configurable */
 	/* TODO remove user name in db path */
 	sql = sqlite3_mprintf ("ATTACH %Q AS maindb", "/home/sylecn/.cache/ibus/pinyin/main.db");
-	r = sqlite3_exec_simple (db, sql);
-	g_assert (r);
+	rb = sqlite3_exec_simple (db, sql);
+	if (! rb) {
+		g_warning ("attach maindb failed, query will not work.");
+		goto attach_fail;
+	}
 	sqlite3_free (sql);
 
 	/* TODO make db path configurable */
 	sql = sqlite3_mprintf ("ATTACH %Q AS userdb", "/home/sylecn/.cache/ibus/pinyin/user-1.0.db");
-	r = sqlite3_exec_simple (db, sql);
-	g_assert (r);
-	sqlite3_free (sql);
-
+	rb = sqlite3_exec_simple (db, sql);
+	if (! rb) {
+		g_warning ("attach userdb failed, query will not work.");
+		goto attach_fail;
+	}
 	appdata->db = db;
+	return;
+
+attach_fail:
+	sqlite3_free (sql);
+	sqlite3_close (db);
+db_fail:
+	appdata->db = NULL;
 }
 
 static void
diff --git a/meson.build b/meson.build
index 2e0e49cd6746c9ef6584349a8a7f346b439048f9..d9bf42f7baa43b67d63f38555c579b7a5b1b67e4 100644
--- a/meson.build
+++ b/meson.build
@@ -1,6 +1,6 @@
 # -*- mode: conf -*-
 project('zero-pinyin-service', ['c', 'cpp'],
-  version: '0.3.1',
+  version: '0.3.2',
   license: 'GPL',
   default_options: [
     'warning_level=2',
diff --git a/zero-pinyin-service.c b/zero-pinyin-service.c
index 2cfdab5c46186ead3caac5d72aa4d70fd10bfa11..908cea2d3c0c117546ca062172f087eb84a7659a 100644
--- a/zero-pinyin-service.c
+++ b/zero-pinyin-service.c
@@ -129,6 +129,7 @@ get_candidates_for_n_pinyin (sqlite3* db,
 	const guint DEFAULT_LIMIT = 50;
 	GList* result = NULL;	/* GList of Candidate */
 
+	g_assert_nonnull (db);
 	g_assert_cmpint (group_size, >=, 1);
 	g_assert_cmpint (group_size, <=, g_list_length (pylist));
 
@@ -201,6 +202,10 @@ get_candidates (sqlite3* db,
 		GVariantBuilder *candidates_builder,
 		GVariantBuilder *matched_lengths_builder)
 {
+	if (! db) {
+		g_warning ("No db connection, can't get candidates.");
+		return;
+	}
 	GList* pylist = NULL;
 	guint pylist_len = 0;