diff --git a/com.emacsos.zero.ZeroPinyinService1.ZeroPinyinServiceInterface.xml b/com.emacsos.zero.ZeroPinyinService1.ZeroPinyinServiceInterface.xml
index f0876deedd51a87de711fd636483ae0a3d60c3fd..24401bc7a9f5a2712696abada9701df91242a3dc 100644
--- a/com.emacsos.zero.ZeroPinyinService1.ZeroPinyinServiceInterface.xml
+++ b/com.emacsos.zero.ZeroPinyinService1.ZeroPinyinServiceInterface.xml
@@ -5,6 +5,7 @@
   <interface name="com.emacsos.zero.ZeroPinyinService1.ZeroPinyinServiceInterface">
     <!--
 	GetCandidates:
+
 	@preedit_str: the preedit string
 	@fetch_size: how many candidates to fetch
 	@candidates: the candidates
@@ -23,6 +24,17 @@
       <arg type="au" name="matched_preedit_str_lengths" direction="out"/>
     </method>
 
+    <!-- DeleteCandidate
+
+	 @candidate: the candidate to delete.
+
+	 This will make given candidate disappear for current user in future
+	 typing. delete single character is not allowed. it will be a no-op.
+    -->
+    <method name="DeleteCandidate">
+      <arg type="s" name="candidate"/>
+    </method>
+
     <method name="Quit"/>
 
     <annotation name="org.gtk.GDBus.C.Name" value="ZeroPinyinService"/>
diff --git a/main.c b/main.c
index 81186ad2320f0089817c685d2393d386f4f9284b..a4bd63fa40b292fa307ad5c3137c59e5adefacd3 100644
--- a/main.c
+++ b/main.c
@@ -1,3 +1,4 @@
+#include <locale.h>
 #include <gio/gio.h>
 #include <glib-unix.h>
 #include "zero-pinyin-service.h"
@@ -51,12 +52,54 @@ on_handle_get_candidates (ZeroPinyinService *object,
 	return TRUE;
 }
 
+static gboolean
+on_handle_delete_candidate (ZeroPinyinService *object,
+			    GDBusMethodInvocation *invocation,
+			    const char *candidate,
+			    AppData *appdata)
+{
+	if (! candidate) {
+		g_dbus_method_invocation_return_value (invocation, NULL);
+		return TRUE;
+	}
+	guint len = g_utf8_strlen (candidate, -1);
+	if (len == 1) {
+		g_message ("delete single character %s is a no-op", candidate);
+		g_dbus_method_invocation_return_value (invocation, NULL);
+		return TRUE;
+	}
+	g_message ("delete candidate %s", candidate);
+
+	/* insert phrase to userdb.not_phrase table. */
+	char *sql = NULL;
+	gboolean rb = FALSE;
+	sql = sqlite3_mprintf ("INSERT INTO userdb.not_phrase (phrase) VALUES (%Q);", candidate);
+	rb = sqlite3_exec_simple (appdata->db, sql);
+	if (! rb) {
+		g_warning ("insert phrase to not_phrase table failed");
+	}
+	sqlite3_free (sql);
+
+	/* delete phrase from userdb.py_phrase_x table. */
+	guint table_suffix = len - 1;
+	sql = sqlite3_mprintf ("DELETE FROM userdb.py_phrase_%u WHERE phrase = %Q;", table_suffix, candidate);
+	rb = sqlite3_exec_simple (appdata->db, sql);
+	if (! rb) {
+		g_warning ("delete phrase from py_phrase_%u table failed", table_suffix);
+	}
+	sqlite3_free (sql);
+
+	g_dbus_method_invocation_return_value (invocation, NULL);
+	return TRUE;
+}
+
 static gboolean
 on_handle_quit (ZeroPinyinService *object,
 		GDBusMethodInvocation *invocation,
 		AppData *appdata)
 {
 	g_application_quit (appdata->app);
+	g_dbus_method_invocation_return_value (invocation, NULL);
 	return TRUE;
 }
 
@@ -75,6 +118,10 @@ on_bus_acquired (GDBusConnection *connection,
 			  "handle-get-candidates",
 			  G_CALLBACK (on_handle_get_candidates),
 			  appdata);
+	g_signal_connect (appdata->interface,
+			  "handle-delete-candidate",
+			  G_CALLBACK (on_handle_delete_candidate),
+			  appdata);
 	g_signal_connect (appdata->interface,
 			  "handle-quit",
 			  G_CALLBACK (on_handle_quit),
@@ -171,6 +218,16 @@ config_db (AppData* appdata)
 		g_warning ("attach userdb failed, query will not work.");
 		goto attach_fail;
 	}
+	sqlite3_free (sql);
+
+	sql = "CREATE TABLE IF NOT EXISTS userdb.not_phrase (phrase TEXT UNIQUE);";
+	rb = sqlite3_exec_simple (db, sql);
+	if (! rb) {
+		g_warning ("create userdb.not_phrase table failed, query will not work.");
+		sql = NULL;
+		goto attach_fail;
+	}
+
 	appdata->db = db;
 	return;
 
@@ -243,6 +300,8 @@ main (int argc, char *argv[])
 	GApplication *app = NULL;
 	int status = 0;
 
+	setlocale (LC_ALL, "");
+
 	app = g_application_new ("com.emacsos.zero.ZeroPinyinServiceApp",
 				 G_APPLICATION_FLAGS_NONE);
 	g_assert_nonnull (app);
diff --git a/meson.build b/meson.build
index 417afdf9c66549089afcd14a1a4d4f8ba19c99d9..a0e565db464df4f132ef3551d2c27912c7243ba0 100644
--- a/meson.build
+++ b/meson.build
@@ -1,6 +1,6 @@
 # -*- mode: conf -*-
 project('zero-pinyin-service', ['c', 'cpp'],
-  version: '0.4.0',
+  version: '0.5.0',
   license: 'GPL',
   default_options: [
     'warning_level=2',
diff --git a/zero-pinyin-service.c b/zero-pinyin-service.c
index 908cea2d3c0c117546ca062172f087eb84a7659a..5f993a83364c33935e1c730c82b9a513f47680fc 100644
--- a/zero-pinyin-service.c
+++ b/zero-pinyin-service.c
@@ -101,7 +101,10 @@ build_sql_for_n_pinyin (GList* pylist,
 		sql, "SELECT user_freq, phrase, freq FROM "
 		"userdb.py_phrase_%u WHERE ", n - 1);
 	sql = g_string_append (sql, where_clause);
-	sql = g_string_append (sql, ") GROUP BY phrase ORDER BY user_freq DESC, freq DESC ");
+	sql = g_string_append (
+		sql, ") "
+		"WHERE phrase NOT IN (SELECT phrase FROM userdb.not_phrase) "
+		"GROUP BY phrase ORDER BY user_freq DESC, freq DESC ");
 	g_string_append_printf (sql, "LIMIT %u;", limit);
 	char* result = sql->str;
 	g_free (where_clause);