diff --git a/src/includes/class.db.sqlite3.php b/src/includes/class.db.sqlite3.php
index 0abeaf2..348244c 100644
--- a/src/includes/class.db.sqlite3.php
+++ b/src/includes/class.db.sqlite3.php
@@ -62,8 +62,16 @@ class Database_Sqlite3 extends Database_Abstract
     /** @var int */
     protected $affected = 0;
 
-    function __construct()
+    /** @var bool */
+    protected $useNormalizedUtf8 = true;
+
+    function __construct(array $params = null)
     {
+        if (is_array($params)) {
+            if (isset($params['useNormalizedUtf8'])) {
+                $this->useNormalizedUtf8 = boolval($params['useNormalizedUtf8']);
+            }
+        }
     }
 
     function connect(array $params): void
@@ -73,8 +81,10 @@ class Database_Sqlite3 extends Database_Abstract
             PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
         );
         $this->dbh = new PDO("sqlite:$filename", null, null, $options); //throws PDOException
-        $this->dbh->sqliteCreateFunction('utf8_lower', [$this, 'utf8lower'], 1);
-        $this->dbh->sqliteCreateCollation('UTF8CI', [$this, 'utf8ci']);
+        $this->dbh->sqliteCreateFunction('utf8_lower', [$this, 'utf8_lower'], 1);
+        $this->dbh->sqliteCreateFunction('utf8_normalized_lower', [$this, 'utf8_normalized_lower'], 1);
+        $this->dbh->sqliteCreateCollation('UTF8CI', [$this, 'collate_utf8ci']);
+        $this->dbh->sqliteCreateCollation('UTF8CI_NORMALIZED', [$this, 'collate_utf8ci_normalized']);
     }
 
     /*
@@ -170,7 +180,10 @@ class Database_Sqlite3 extends Database_Abstract
     function like(string $column, string $format, string $string): string
     {
         $column = str_replace('"', '""', $column);
-        return 'utf8_lower("'. $column. '") LIKE '. $this->quoteForLike($format, mb_strtolower($string, 'UTF-8'));
+        if ($this->useNormalizedUtf8) {
+            return 'utf8_normalized_lower("'. $column. '") LIKE '. $this->quoteForLike($format, $this->utf8_normalized_lower($string));
+        }
+        return 'utf8_lower("'. $column. '") LIKE '. $this->quoteForLike($format, $this->utf8_lower($string));
     }
 
     function lastInsertId(?string $name = null): ?string
@@ -204,14 +217,102 @@ class Database_Sqlite3 extends Database_Abstract
         return false;
     }
 
-    public function utf8lower($value)
+    public function utf8_lower($value): string
     {
         if (is_null($value)) return '';
         return mb_strtolower((string)$value, 'UTF-8');
     }
 
-    public function utf8ci(string $str1, string $str2): int
+    public function utf8_normalized_lower($value): string
+    {
+        if (is_null($value)) return '';
+        $value = self::normalizeValue((string) $value);
+        return mb_strtolower($value, 'UTF-8');
+    }
+
+    public function collate_utf8ci(string $str1, string $str2): int
     {
         return strcmp(mb_strtolower($str1, 'UTF-8'), mb_strtolower($str2, 'UTF-8'));
     }
+
+    public function collate_utf8ci_normalized(string $str1, string $str2): int
+    {
+        $str1 = self::normalizeValue($str1);
+        $str2 = self::normalizeValue($str2);
+        return strcmp(mb_strtolower($str1, 'UTF-8'), mb_strtolower($str2, 'UTF-8'));
+    }
+
+    public static function normalizeValue(string $str): string
+    {
+        $str = Normalizer::normalize($str, Normalizer::FORM_KD);
+
+        if (false === preg_match_all("/./u", $str, $m)) {
+            $ea = error_get_last();
+            $error = ($ea && isset($ea['message'])) ? $ea['message'] : "preg_match_all() failed";
+            throw new Exception($error);
+        }
+        $chars = $m[0];
+        static $map = [
+            // https://en.wikipedia.org/wiki/Combining_character
+            "\u{0300}" => '', "\u{0301}" => '', "\u{0302}" => '', "\u{0303}" => '', "\u{0304}" => '', "\u{0305}" => '', "\u{0306}" => '', "\u{0307}" => '',
+            "\u{0308}" => '', "\u{0309}" => '', "\u{030a}" => '', "\u{030b}" => '', "\u{030c}" => '', "\u{030d}" => '', "\u{030e}" => '', "\u{030f}" => '',
+            "\u{0310}" => '', "\u{0311}" => '', "\u{0312}" => '', "\u{0313}" => '', "\u{0314}" => '', "\u{0315}" => '', "\u{0316}" => '', "\u{0317}" => '',
+            "\u{0318}" => '', "\u{0319}" => '', "\u{031a}" => '', "\u{031b}" => '', "\u{031c}" => '', "\u{031d}" => '', "\u{031e}" => '', "\u{031f}" => '',
+            "\u{0320}" => '', "\u{0321}" => '', "\u{0322}" => '', "\u{0323}" => '', "\u{0324}" => '', "\u{0325}" => '', "\u{0326}" => '', "\u{0327}" => '',
+            "\u{0328}" => '', "\u{0329}" => '', "\u{032a}" => '', "\u{032b}" => '', "\u{032c}" => '', "\u{032d}" => '', "\u{032e}" => '', "\u{032f}" => '',
+            "\u{0330}" => '', "\u{0331}" => '', "\u{0332}" => '', "\u{0333}" => '', "\u{0334}" => '', "\u{0335}" => '', "\u{0336}" => '', "\u{0337}" => '',
+            "\u{0338}" => '', "\u{0339}" => '', "\u{033a}" => '', "\u{033b}" => '', "\u{033c}" => '', "\u{033d}" => '', "\u{033e}" => '', "\u{033f}" => '',
+            "\u{0340}" => '', "\u{0341}" => '', "\u{0342}" => '', "\u{0343}" => '', "\u{0344}" => '', "\u{0345}" => '', "\u{0346}" => '', "\u{0347}" => '',
+            "\u{0348}" => '', "\u{0349}" => '', "\u{034a}" => '', "\u{034b}" => '', "\u{034c}" => '', "\u{034d}" => '', "\u{034e}" => '', "\u{034f}" => '',
+            "\u{0350}" => '', "\u{0351}" => '', "\u{0352}" => '', "\u{0353}" => '', "\u{0354}" => '', "\u{0355}" => '', "\u{0356}" => '', "\u{0357}" => '',
+            "\u{0358}" => '', "\u{0359}" => '', "\u{035a}" => '', "\u{035b}" => '', "\u{035c}" => '', "\u{035d}" => '', "\u{035e}" => '', "\u{035f}" => '',
+            "\u{0360}" => '', "\u{0361}" => '', "\u{0362}" => '', "\u{0363}" => '', "\u{0364}" => '', "\u{0365}" => '', "\u{0366}" => '', "\u{0367}" => '',
+            "\u{0368}" => '', "\u{0369}" => '', "\u{036a}" => '', "\u{036b}" => '', "\u{036c}" => '', "\u{036d}" => '', "\u{036e}" => '', "\u{036f}" => '',
+
+            "\u{1ab0}" => '', "\u{1ab1}" => '', "\u{1ab2}" => '', "\u{1ab3}" => '', "\u{1ab4}" => '', "\u{1ab5}" => '', "\u{1ab6}" => '', "\u{1ab7}" => '',
+            "\u{1ab8}" => '', "\u{1ab9}" => '', "\u{1aba}" => '', "\u{1abb}" => '', "\u{1abc}" => '', "\u{1abd}" => '', "\u{1abe}" => '', "\u{1abf}" => '',
+            "\u{1ac0}" => '', "\u{1ac1}" => '', "\u{1ac2}" => '', "\u{1ac3}" => '', "\u{1ac4}" => '', "\u{1ac5}" => '', "\u{1ac6}" => '', "\u{1ac7}" => '',
+            "\u{1ac8}" => '', "\u{1ac9}" => '', "\u{1aca}" => '', "\u{1acb}" => '', "\u{1acc}" => '', "\u{1acd}" => '', "\u{1ace}" => '', "\u{1acf}" => '',
+            "\u{1ad0}" => '', "\u{1ad1}" => '', "\u{1ad2}" => '', "\u{1ad3}" => '', "\u{1ad4}" => '', "\u{1ad5}" => '', "\u{1ad6}" => '', "\u{1ad7}" => '',
+            "\u{1ad8}" => '', "\u{1ad9}" => '', "\u{1ada}" => '', "\u{1adb}" => '', "\u{1adc}" => '', "\u{1add}" => '', "\u{1ade}" => '', "\u{1adf}" => '',
+            "\u{1ae0}" => '', "\u{1ae1}" => '', "\u{1ae2}" => '', "\u{1ae3}" => '', "\u{1ae4}" => '', "\u{1ae5}" => '', "\u{1ae6}" => '', "\u{1ae7}" => '',
+            "\u{1ae8}" => '', "\u{1ae9}" => '', "\u{1aea}" => '', "\u{1aeb}" => '', "\u{1aec}" => '', "\u{1aed}" => '', "\u{1aee}" => '', "\u{1aef}" => '',
+            "\u{1af0}" => '', "\u{1af1}" => '', "\u{1af2}" => '', "\u{1af3}" => '', "\u{1af4}" => '', "\u{1af5}" => '', "\u{1af6}" => '', "\u{1af7}" => '',
+            "\u{1af8}" => '', "\u{1af9}" => '', "\u{1afa}" => '', "\u{1afb}" => '', "\u{1afc}" => '', "\u{1afd}" => '', "\u{1afe}" => '', "\u{1aff}" => '',
+
+            "\u{1dc0}" => '', "\u{1dc1}" => '', "\u{1dc2}" => '', "\u{1dc3}" => '', "\u{1dc4}" => '', "\u{1dc5}" => '', "\u{1dc6}" => '', "\u{1dc7}" => '',
+            "\u{1dc8}" => '', "\u{1dc9}" => '', "\u{1dca}" => '', "\u{1dcb}" => '', "\u{1dcc}" => '', "\u{1dcd}" => '', "\u{1dce}" => '', "\u{1dcf}" => '',
+            "\u{1dd0}" => '', "\u{1dd1}" => '', "\u{1dd2}" => '', "\u{1dd3}" => '', "\u{1dd4}" => '', "\u{1dd5}" => '', "\u{1dd6}" => '', "\u{1dd7}" => '',
+            "\u{1dd8}" => '', "\u{1dd9}" => '', "\u{1dda}" => '', "\u{1ddb}" => '', "\u{1ddc}" => '', "\u{1ddd}" => '', "\u{1dde}" => '', "\u{1ddf}" => '',
+            "\u{1de0}" => '', "\u{1de1}" => '', "\u{1de2}" => '', "\u{1de3}" => '', "\u{1de4}" => '', "\u{1de5}" => '', "\u{1de6}" => '', "\u{1de7}" => '',
+            "\u{1de8}" => '', "\u{1de9}" => '', "\u{1dea}" => '', "\u{1deb}" => '', "\u{1dec}" => '', "\u{1ded}" => '', "\u{1dee}" => '', "\u{1def}" => '',
+            "\u{1df0}" => '', "\u{1df1}" => '', "\u{1df2}" => '', "\u{1df3}" => '', "\u{1df4}" => '', "\u{1df5}" => '', "\u{1df6}" => '', "\u{1df7}" => '',
+            "\u{1df8}" => '', "\u{1df9}" => '', "\u{1dfa}" => '', "\u{1dfb}" => '', "\u{1dfc}" => '', "\u{1dfd}" => '', "\u{1dfe}" => '', "\u{1dff}" => '',
+
+            "\u{20d0}" => '', "\u{20d1}" => '', "\u{20d2}" => '', "\u{20d3}" => '', "\u{20d4}" => '', "\u{20d5}" => '', "\u{20d6}" => '', "\u{20d7}" => '',
+            "\u{20d8}" => '', "\u{20d9}" => '', "\u{20da}" => '', "\u{20db}" => '', "\u{20dc}" => '', "\u{20dd}" => '', "\u{20de}" => '', "\u{20df}" => '',
+            "\u{20e0}" => '', "\u{20e1}" => '', "\u{20e2}" => '', "\u{20e3}" => '', "\u{20e4}" => '', "\u{20e5}" => '', "\u{20e6}" => '', "\u{20e7}" => '',
+            "\u{20e8}" => '', "\u{20e9}" => '', "\u{20ea}" => '', "\u{20eb}" => '', "\u{20ec}" => '', "\u{20ed}" => '', "\u{20ee}" => '', "\u{20ef}" => '',
+            "\u{20f0}" => '', "\u{20f1}" => '', "\u{20f2}" => '', "\u{20f3}" => '', "\u{20f4}" => '', "\u{20f5}" => '', "\u{20f6}" => '', "\u{20f7}" => '',
+            "\u{20f8}" => '', "\u{20f9}" => '', "\u{20fa}" => '', "\u{20fb}" => '', "\u{20fc}" => '', "\u{20fd}" => '', "\u{20fe}" => '', "\u{20ff}" => '',
+
+            "\u{fe20}" => '', "\u{fe21}" => '', "\u{fe22}" => '', "\u{fe23}" => '', "\u{fe24}" => '', "\u{fe25}" => '', "\u{fe26}" => '', "\u{fe27}" => '',
+            "\u{fe28}" => '', "\u{fe29}" => '', "\u{fe2a}" => '', "\u{fe2b}" => '', "\u{fe2c}" => '', "\u{fe2d}" => '', "\u{fe2e}" => '', "\u{fe2f}" => '',
+
+            'Æ' => 'AE',  // "U+00c6"
+            'æ' => 'ae',  // "U+00e6"
+            'Œ' => 'OE',  // "U+0152"
+            'œ' => 'oe',  // "U+0153"
+        ];
+
+        $len = count($chars);
+        for ($i = 0; $i < $len; $i++) {
+            $unichar = $chars[$i];
+            if (isset($map[$unichar])) {
+                $chars[$i] = $map[$unichar];
+            }
+        }
+        return implode('', $chars);
+    }
+
 }