diff --git a/CHANGELOG.md b/CHANGELOG.md
index 093b71bc..01c4911e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,6 @@
-## 3.2.1-RC (2020-12-20)
+## 3.3.0-RC (2020-12-20)
 * Fix configure external directory to database files
+* `SomeDatabase::getByNumericCode` now accept strings instead of ints, `SomeEntity::getNumericCode` now return strings
 
 ## 3.2.0 (2020-12-13)
 * Allow to configure own translation driver
diff --git a/src/AbstractDatabase.php b/src/AbstractDatabase.php
index 5a154aea..922bfeb4 100644
--- a/src/AbstractDatabase.php
+++ b/src/AbstractDatabase.php
@@ -69,7 +69,7 @@ public function __construct(
     abstract public static function getISONumber(): string;
 
     /**
-     * @param mixed[] $entry
+     * @param array<string, string> $entry
      *
      * @return object
      */
diff --git a/src/AbstractNotPartitionedDatabase.php b/src/AbstractNotPartitionedDatabase.php
index b5475fd7..e02feace 100644
--- a/src/AbstractNotPartitionedDatabase.php
+++ b/src/AbstractNotPartitionedDatabase.php
@@ -50,7 +50,6 @@ private function getIndex(string $indexedFieldName): array
                     foreach ($indexedFields as $indexName => $indexDefinition) {
                         if (is_array($indexDefinition)) {
                             // compound index
-
                             // iteratively create hierarchy of array indexes
                             $reference = &$this->index[$indexName];
                             foreach ($indexDefinition as $indexDefinitionPart) {
@@ -64,9 +63,11 @@ private function getIndex(string $indexedFieldName): array
                                 } else {
                                     $indexDefinitionPartValue = $entryArray[$indexDefinitionPart];
                                 }
+
                                 if (!isset($reference[$indexDefinitionPartValue])) {
                                     $reference[$indexDefinitionPartValue] = [];
                                 }
+
                                 $reference = &$reference[$indexDefinitionPartValue];
                             }
 
@@ -75,10 +76,12 @@ private function getIndex(string $indexedFieldName): array
                         } else {
                             // single index
                             $indexName = $indexDefinition;
+
                             // skip empty field
                             if (empty($entryArray[$indexDefinition])) {
                                 continue;
                             }
+
                             // add to indexUA
                             $this->index[$indexName][$entryArray[$indexDefinition]] = $entry;
                         }
@@ -102,11 +105,13 @@ private function getIndex(string $indexedFieldName): array
     }
 
     /**
+     * @param string $indexedFieldName
      * @param string $fieldValue
      *
-     * @return object|mixed[]|null
+     * @return null|object|object[] null when not found, object when found by single-field index,
+     *         object[] when found by compound index
      */
-    protected function find(string $indexedFieldName, $fieldValue)
+    protected function find(string $indexedFieldName, string $fieldValue)
     {
         $fieldIndex = $this->getIndex($indexedFieldName);
 
diff --git a/src/Database/Countries.php b/src/Database/Countries.php
index 09a93f42..368aa17f 100644
--- a/src/Database/Countries.php
+++ b/src/Database/Countries.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\AbstractNotPartitionedDatabase;
 use Sokil\IsoCodes\Database\Countries\Country;
 
+/**
+ * @method Country|null find(string $indexedFieldName, string $fieldValue)
+ */
 class Countries extends AbstractNotPartitionedDatabase
 {
     public static function getISONumber(): string
@@ -15,7 +18,7 @@ public static function getISONumber(): string
     }
 
     /**
-     * @param string[] $entry
+     * @param array<string, string> $entry
      */
     protected function arrayToEntry(array $entry): Country
     {
@@ -67,6 +70,6 @@ public function getByNumericCode($code): ?Country
             throw new \TypeError('Argument must be int or string');
         }
 
-        return $this->find('numeric', $code);
+        return $this->find('numeric', (string)$code);
     }
 }
diff --git a/src/Database/Countries/Country.php b/src/Database/Countries/Country.php
index 7203907d..3147598c 100644
--- a/src/Database/Countries/Country.php
+++ b/src/Database/Countries/Country.php
@@ -15,7 +15,7 @@ class Country
     private $name;
 
     /**
-     * @var string
+     * @var string|null
      */
     private $localName;
 
diff --git a/src/Database/Currencies.php b/src/Database/Currencies.php
index e8bfca6e..e955ccdf 100644
--- a/src/Database/Currencies.php
+++ b/src/Database/Currencies.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\AbstractNotPartitionedDatabase;
 use Sokil\IsoCodes\Database\Currencies\Currency;
 
+/**
+ * @method Currency|null find(string $indexedFieldName, string $fieldValue)
+ */
 class Currencies extends AbstractNotPartitionedDatabase
 {
     public static function getISONumber(): string
@@ -15,7 +18,7 @@ public static function getISONumber(): string
     }
 
     /**
-     * @param mixed[] $entry
+     * @param array<string, string> $entry
      */
     protected function arrayToEntry(array $entry): Currency
     {
@@ -23,7 +26,7 @@ protected function arrayToEntry(array $entry): Currency
             $this->translationDriver,
             $entry['name'],
             $entry['alpha_3'],
-            (int)$entry['numeric']
+            $entry['numeric']
         );
     }
 
@@ -43,8 +46,22 @@ public function getByLetterCode(string $code): ?Currency
         return $this->find('alpha_3', $code);
     }
 
-    public function getByNumericCode(int $code): ?Currency
+    /**
+     * Using int code argument is deprecated due to it can be with leading 0 (e.g. '042').
+     * Please, use numeric strings.
+     *
+     * @param string|int $code
+     *
+     * @return Currency|null
+     *
+     * @throws \TypeError
+     */
+    public function getByNumericCode($code): ?Currency
     {
-        return $this->find('numeric', $code);
+        if (!is_numeric($code)) {
+            throw new \TypeError('Argument must be int or string');
+        }
+
+        return $this->find('numeric', (string)$code);
     }
 }
diff --git a/src/Database/Currencies/Currency.php b/src/Database/Currencies/Currency.php
index 70b3e70b..dc86d50a 100644
--- a/src/Database/Currencies/Currency.php
+++ b/src/Database/Currencies/Currency.php
@@ -10,12 +10,14 @@
 class Currency
 {
     /**
+     * Alpha3
+     *
      * @var string
      */
     private $letterCode;
 
     /**
-     * @var integer
+     * @var string
      */
     private $numericCode;
 
@@ -25,7 +27,7 @@ class Currency
     private $name;
 
     /**
-     * @var string
+     * @var string|null
      */
     private $localName;
 
@@ -38,7 +40,7 @@ public function __construct(
         TranslatorInterface $translator,
         string $name,
         string $letterCode,
-        int $numericCode
+        string $numericCode
     ) {
         $this->translator = $translator;
         $this->name = $name;
@@ -68,7 +70,7 @@ public function getLetterCode(): string
         return $this->letterCode;
     }
 
-    public function getNumericCode(): int
+    public function getNumericCode(): string
     {
         return $this->numericCode;
     }
diff --git a/src/Database/HistoricCountries.php b/src/Database/HistoricCountries.php
index 25c75214..9b26e8b7 100644
--- a/src/Database/HistoricCountries.php
+++ b/src/Database/HistoricCountries.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\AbstractNotPartitionedDatabase;
 use Sokil\IsoCodes\Database\HistoricCountries\Country;
 
+/**
+ * @method Country|null find(string $indexedFieldName, string $fieldValue)
+ */
 class HistoricCountries extends AbstractNotPartitionedDatabase
 {
     public static function getISONumber(): string
@@ -15,7 +18,7 @@ public static function getISONumber(): string
     }
 
     /**
-     * @param string[] $entry
+     * @param array<string, string> $entry
      */
     protected function arrayToEntry(array $entry): Country
     {
@@ -26,7 +29,7 @@ protected function arrayToEntry(array $entry): Country
             $entry['alpha_3'],
             $entry['alpha_2'],
             $entry['withdrawal_date'],
-            !empty($entry['numeric']) ? (int)$entry['numeric'] : null
+            !empty($entry['numeric']) ? $entry['numeric'] : null
         );
     }
 
@@ -58,8 +61,22 @@ public function getByAlpha2(string $code): ?Country
         return $this->find('alpha_2', $code);
     }
 
-    public function getByNumericCode(int $code): ?Country
+    /**
+     * Using int code argument is deprecated due to it can be with leading 0 (e.g. '042').
+     * Please, use numeric strings.
+     *
+     * @param string|int $code
+     *
+     * @return Country|null
+     *
+     * @throws \TypeError
+     */
+    public function getByNumericCode($code): ?Country
     {
-        return $this->find('numeric', $code);
+        if (!is_numeric($code)) {
+            throw new \TypeError('Argument must be int or string');
+        }
+
+        return $this->find('numeric', (string)$code);
     }
 }
diff --git a/src/Database/HistoricCountries/Country.php b/src/Database/HistoricCountries/Country.php
index 494d3c37..111917ee 100644
--- a/src/Database/HistoricCountries/Country.php
+++ b/src/Database/HistoricCountries/Country.php
@@ -15,7 +15,7 @@ class Country
     private $name;
 
     /**
-     * @var string
+     * @var string|null
      */
     private $localName;
 
@@ -40,7 +40,7 @@ class Country
     private $withdrawalDate;
 
     /**
-     * @var integer|null
+     * @var string|null
      */
     public $numericCode;
 
@@ -56,7 +56,7 @@ public function __construct(
         string $alpha3,
         string $alpha2,
         string $withdrawalDate,
-        ?int $numericCode = null
+        ?string $numericCode = null
     ) {
         $this->translator = $translator;
         $this->name = $name;
@@ -104,7 +104,7 @@ public function getWithdrawalDate(): string
         return $this->withdrawalDate;
     }
 
-    public function getNumericCode(): ?int
+    public function getNumericCode(): ?string
     {
         return $this->numericCode;
     }
diff --git a/src/Database/Languages.php b/src/Database/Languages.php
index 6c904edd..f6832807 100644
--- a/src/Database/Languages.php
+++ b/src/Database/Languages.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\AbstractNotPartitionedDatabase;
 use Sokil\IsoCodes\Database\Languages\Language;
 
+/**
+ * @method Language|null find(string $indexedFieldName, string $fieldValue)
+ */
 class Languages extends AbstractNotPartitionedDatabase implements LanguagesInterface
 {
     public static function getISONumber(): string
@@ -15,7 +18,7 @@ public static function getISONumber(): string
     }
 
     /**
-     * @param string[] $entry
+     * @param array<string, string> $entry
      */
     protected function arrayToEntry(array $entry): Language
     {
diff --git a/src/Database/Languages/Language.php b/src/Database/Languages/Language.php
index 5ae1ea7f..7987e451 100644
--- a/src/Database/Languages/Language.php
+++ b/src/Database/Languages/Language.php
@@ -38,7 +38,7 @@ class Language
     private $name;
 
     /**
-     * @var string
+     * @var string|null
      */
     private $localName;
 
diff --git a/src/Database/LanguagesPartitioned.php b/src/Database/LanguagesPartitioned.php
index c718b852..242b861e 100644
--- a/src/Database/LanguagesPartitioned.php
+++ b/src/Database/LanguagesPartitioned.php
@@ -15,7 +15,7 @@ public static function getISONumber(): string
     }
 
     /**
-     * @param string[] $entry
+     * @param array<string, string> $entry
      */
     protected function arrayToEntry(array $entry): Language
     {
diff --git a/src/Database/Scripts.php b/src/Database/Scripts.php
index 5fca31fe..70a9fd08 100644
--- a/src/Database/Scripts.php
+++ b/src/Database/Scripts.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\AbstractNotPartitionedDatabase;
 use Sokil\IsoCodes\Database\Scripts\Script;
 
+/**
+ * @method Script|null find(string $indexedFieldName, string $fieldValue)
+ */
 class Scripts extends AbstractNotPartitionedDatabase
 {
     public static function getISONumber(): string
@@ -15,7 +18,8 @@ public static function getISONumber(): string
     }
 
     /**
-     * @param string[] $entry
+     * @param array<string, string> $entry
+     *
      */
     protected function arrayToEntry(array $entry): Script
     {
@@ -23,7 +27,7 @@ protected function arrayToEntry(array $entry): Script
             $this->translationDriver,
             $entry['name'],
             $entry['alpha_4'],
-            (int)$entry['numeric']
+            $entry['numeric']
         );
     }
 
@@ -43,8 +47,22 @@ public function getByAlpha4(string $alpha4): ?Script
         return $this->find('alpha_4', $alpha4);
     }
 
-    public function getByNumericCode(int $code): ?Script
+    /**
+     * Using int code argument is deprecated due to it can be with leading 0 (e.g. '042').
+     * Please, use numeric strings.
+     *
+     * @param string|int $code
+     *
+     * @return Script|null
+     *
+     * @throws \TypeError
+     */
+    public function getByNumericCode($code): ?Script
     {
-        return $this->find('numeric', $code);
+        if (!is_numeric($code)) {
+            throw new \TypeError('Argument must be int or string');
+        }
+
+        return $this->find('numeric', (string)$code);
     }
 }
diff --git a/src/Database/Scripts/Script.php b/src/Database/Scripts/Script.php
index 16b3dec5..cf006f98 100644
--- a/src/Database/Scripts/Script.php
+++ b/src/Database/Scripts/Script.php
@@ -15,7 +15,7 @@ class Script
     private $name;
 
     /**
-     * @var string
+     * @var string|null
      */
     private $localName;
 
@@ -25,7 +25,7 @@ class Script
     private $alpha4;
 
     /**
-     * @var integer
+     * @var string
      */
     private $numericCode;
 
@@ -38,7 +38,7 @@ public function __construct(
         TranslatorInterface $translator,
         string $name,
         string $alpha4,
-        int $numericCode
+        string $numericCode
     ) {
         $this->translator = $translator;
         $this->name = $name;
@@ -46,7 +46,6 @@ public function __construct(
         $this->numericCode = $numericCode;
     }
 
-
     public function getName(): string
     {
         return $this->name;
@@ -69,7 +68,7 @@ public function getAlpha4(): string
         return $this->alpha4;
     }
 
-    public function getNumericCode(): int
+    public function getNumericCode(): string
     {
         return $this->numericCode;
     }
diff --git a/src/Database/Subdivisions.php b/src/Database/Subdivisions.php
index c5a1a668..e08b5b3d 100644
--- a/src/Database/Subdivisions.php
+++ b/src/Database/Subdivisions.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\AbstractNotPartitionedDatabase;
 use Sokil\IsoCodes\Database\Subdivisions\Subdivision;
 
+/**
+ * @method Subdivision|Subdivision[]|null find(string $indexedFieldName, string $fieldValue)
+ */
 class Subdivisions extends AbstractNotPartitionedDatabase implements SubdivisionsInterface
 {
     public static function getISONumber(): string
@@ -15,7 +18,7 @@ public static function getISONumber(): string
     }
 
     /**
-     * @param mixed[] $entry
+     * @param array<string, string> $entry
      */
     protected function arrayToEntry(array $entry): Subdivision
     {
diff --git a/src/Database/Subdivisions/Subdivision.php b/src/Database/Subdivisions/Subdivision.php
index c9035bf0..3364e115 100644
--- a/src/Database/Subdivisions/Subdivision.php
+++ b/src/Database/Subdivisions/Subdivision.php
@@ -15,7 +15,7 @@ class Subdivision
     private $name;
 
     /**
-     * @var string
+     * @var string|null
      */
     private $localName;
 
diff --git a/src/Database/SubdivisionsPartitioned.php b/src/Database/SubdivisionsPartitioned.php
index f56fd7b0..27581c90 100644
--- a/src/Database/SubdivisionsPartitioned.php
+++ b/src/Database/SubdivisionsPartitioned.php
@@ -15,7 +15,7 @@ public static function getISONumber(): string
     }
 
     /**
-     * @param mixed[] $entry
+     * @param array<string, string> $entry
      */
     protected function arrayToEntry(array $entry): Subdivision
     {
diff --git a/tests/Database/CurrenciesTest.php b/tests/Database/CurrenciesTest.php
index 0c4369a2..7eda5ac8 100644
--- a/tests/Database/CurrenciesTest.php
+++ b/tests/Database/CurrenciesTest.php
@@ -10,7 +10,6 @@
 
 class CurrenciesTest extends TestCase
 {
-
     public function testIterator(): void
     {
         $isoCodes = new IsoCodesFactory();
@@ -28,6 +27,7 @@ public function testGetByLetterCode(): void
         $isoCodes = new IsoCodesFactory();
 
         $currencies = $isoCodes->getCurrencies();
+
         $currency = $currencies->getByLetterCode('CZK');
 
         $this->assertInstanceOf(
@@ -51,17 +51,28 @@ public function testGetByLetterCode(): void
         );
 
         $this->assertSame(
-            203,
+            '203',
             $currency->getNumericCode()
         );
     }
 
-    public function testGetByNumericCode(): void
+    public function getByNumericCodeDataProvider(): array
+    {
+        return [
+            ['203'],
+            [203],
+        ];
+    }
+
+    /**
+     * @dataProvider getByNumericCodeDataProvider
+     */
+    public function testGetByNumericCode($code): void
     {
         $isoCodes = new IsoCodesFactory();
 
         $currencies = $isoCodes->getCurrencies();
-        $currency = $currencies->getByNumericCode(203);
+        $currency = $currencies->getByNumericCode($code);
 
         $this->assertEquals(
             'Czech Koruna',
@@ -73,4 +84,17 @@ public function testGetByNumericCode(): void
             $currency->getLocalName()
         );
     }
+
+    public function testGetByNumericCodeLeadingZeroes(): void
+    {
+        $isoCodes = new IsoCodesFactory();
+
+        $currencies = $isoCodes->getCurrencies();
+        $currency = $currencies->getByNumericCode('051');
+
+        $this->assertEquals(
+            'AMD',
+            $currency->getLetterCode()
+        );
+    }
 }
diff --git a/tests/Database/HistoricCountriesTest.php b/tests/Database/HistoricCountriesTest.php
index 789fc259..a597217b 100644
--- a/tests/Database/HistoricCountriesTest.php
+++ b/tests/Database/HistoricCountriesTest.php
@@ -62,7 +62,7 @@ public function testGetByAlpha4(): void
         );
 
         $this->assertSame(
-            180,
+            '180',
             $country->getNumericCode()
         );
     }
@@ -134,7 +134,7 @@ public function testGetByNumericCode(): void
         $isoCodes = new IsoCodesFactory();
 
         $countries = $isoCodes->getHistoricCountries();
-        $country = $countries->getByNumericCode(180);
+        $country = $countries->getByNumericCode('180');
 
         $this->assertInstanceOf(
             Country::class,
@@ -156,7 +156,7 @@ public function testGetLocalByNumericCode(): void
         $isoCodes = new IsoCodesFactory();
 
         $countries = $isoCodes->getHistoricCountries();
-        $country = $countries->getByNumericCode(180);
+        $country = $countries->getByNumericCode('180');
 
         $this->assertInstanceOf(
             Country::class,
diff --git a/tests/Database/ScriptsTest.php b/tests/Database/ScriptsTest.php
index ecd94b06..8c8165f2 100644
--- a/tests/Database/ScriptsTest.php
+++ b/tests/Database/ScriptsTest.php
@@ -52,7 +52,7 @@ public function testGetByAlpha4(): void
         );
 
         $this->assertSame(
-            239,
+            '239',
             $script->getNumericCode()
         );
     }
@@ -62,7 +62,7 @@ public function testGetByNumericCode(): void
         $isoCodes = new IsoCodesFactory();
 
         $scripts = $isoCodes->getScripts();
-        $script = $scripts->getByNumericCode(239);
+        $script = $scripts->getByNumericCode('239');
 
         $this->assertInstanceOf(
             Script::class,