diff --git a/README.md b/README.md
index 0c2a1ed..98769de 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@ const parse = require('mrz').parse;
 
 const mrz = [
   'I<UTOD23145890<1233<<<<<<<<<<<',
-  '7408122F1204159UTO<<<<<<<<<<<6',
+  '7408122F1204159UTO<<<<<<<<<<<2',
   'ERIKSSON<<ANNA<MARIA<<<<<<<<<<',
 ];
 
diff --git a/src/parse/__tests__/td1.test.ts b/src/parse/__tests__/td1.test.ts
index c1503a0..0b89373 100644
--- a/src/parse/__tests__/td1.test.ts
+++ b/src/parse/__tests__/td1.test.ts
@@ -48,6 +48,192 @@ describe('parse TD1', () => {
     });
   });
 
+  it('Portuguese ID - valid', () => {
+    // source: https://media.timeout.com/images/106144795/image.jpg
+    const MRZ = [
+      'I<PRT007777779<ZZ92<<<<<<<<<<<',
+      '8303143M3405282PRT<<<<<<<<<<<2',
+      'CACADOR<DE<ARAUJO<<ANDRE<ESTEV',
+    ];
+
+    const result = parse(MRZ);
+
+    expect(result).toMatchObject({
+      format: 'TD1',
+      valid: true,
+      documentNumber: result.fields.documentNumber,
+    });
+
+    expect(result.fields).toStrictEqual({
+      documentCode: 'I',
+      issuingState: 'PRT',
+      documentNumber: '007777779ZZ9',
+      documentNumberCheckDigit: '2',
+      birthDate: '830314',
+      birthDateCheckDigit: '3',
+      sex: 'male',
+      expirationDate: '340528',
+      expirationDateCheckDigit: '2',
+      nationality: 'PRT',
+      optional1: 'ZZ92',
+      optional2: '',
+      compositeCheckDigit: '2',
+      lastName: 'CACADOR DE ARAUJO',
+      firstName: 'ANDRE ESTEV',
+    });
+
+    const optional1Details = result.details.find(
+      (f) => f.field === 'optional1',
+    );
+
+    expect(optional1Details).toMatchObject({
+      value: 'ZZ92',
+      line: 0,
+      start: 15,
+      end: 19,
+    });
+  });
+
+  it('Portuguese ID PRT-BO-04001 - valid', () => {
+    // source: https://www.consilium.europa.eu/prado/en/PRT-BO-04001/index.html
+    const MRZ = [
+      'I<PRT007666667<ZZ00<<<<<<<<<<<',
+      '8303143M3405293PRT<<<<<<<<<<<4',
+      'CACADOR<DE<ARAUJO<<ANDRE<ESTEV',
+    ];
+
+    const result = parse(MRZ);
+
+    expect(result).toMatchObject({
+      format: 'TD1',
+      valid: true,
+      documentNumber: result.fields.documentNumber,
+    });
+
+    expect(result.fields).toStrictEqual({
+      documentCode: 'I',
+      issuingState: 'PRT',
+      documentNumber: '007666667ZZ0',
+      documentNumberCheckDigit: '0',
+      birthDate: '830314',
+      birthDateCheckDigit: '3',
+      sex: 'male',
+      expirationDate: '340529',
+      expirationDateCheckDigit: '3',
+      nationality: 'PRT',
+      optional1: 'ZZ00',
+      optional2: '',
+      compositeCheckDigit: '4',
+      lastName: 'CACADOR DE ARAUJO',
+      firstName: 'ANDRE ESTEV',
+    });
+
+    const optional1Details = result.details.find(
+      (f) => f.field === 'optional1',
+    );
+
+    expect(optional1Details).toMatchObject({
+      value: 'ZZ00',
+      line: 0,
+      start: 15,
+      end: 19,
+    });
+  });
+
+  it('Belgium ID BEL-BO-11005 - valid', () => {
+    // source: https://www.consilium.europa.eu/prado/en/BEL-BO-11005/index.html
+    // Changed the country code from UTO to BEL to make it pass the country validation,
+    // but that this part does not affect any check digit checks.
+    const MRZ = [
+      'IDBEL600001795<0152<<<<<<<<<<<',
+      '1301014F2311207BEL130101987398',
+      'SPECIMEN<<SPECIMEN<<<<<<<<<<<<',
+    ];
+
+    const result = parse(MRZ);
+
+    expect(result).toMatchObject({
+      format: 'TD1',
+      valid: true,
+      documentNumber: result.fields.documentNumber,
+    });
+
+    expect(result.fields).toStrictEqual({
+      documentCode: 'ID',
+      issuingState: 'BEL',
+      documentNumber: '600001795015',
+      documentNumberCheckDigit: '2',
+      birthDate: '130101',
+      birthDateCheckDigit: '4',
+      sex: 'female',
+      expirationDate: '231120',
+      expirationDateCheckDigit: '7',
+      nationality: 'BEL',
+      optional1: '0152',
+      optional2: '13010198739',
+      compositeCheckDigit: '8',
+      lastName: 'SPECIMEN',
+      firstName: 'SPECIMEN',
+    });
+
+    const optional1Details = result.details.find(
+      (f) => f.field === 'optional1',
+    );
+
+    expect(optional1Details).toMatchObject({
+      value: '0152',
+      line: 0,
+      start: 15,
+      end: 19,
+    });
+  });
+
+  it('Finland ID FIN-BO-12001 - valid', () => {
+    // source: https://www.consilium.europa.eu/prado/en/FIN-BO-12001/index.html
+    const MRZ = [
+      'I<FINXA10000585010195<112X<<<<',
+      '9501016F2803135FIN<<<<<<<<<<<7',
+      'SPECIMEN<TRAVEL<<VILMA<SOFIA<<',
+    ];
+
+    const result = parse(MRZ);
+
+    expect(result).toMatchObject({
+      format: 'TD1',
+      valid: true,
+      documentNumber: result.fields.documentNumber,
+    });
+
+    expect(result.fields).toStrictEqual({
+      documentCode: 'I',
+      issuingState: 'FIN',
+      documentNumber: 'XA1000058',
+      documentNumberCheckDigit: '5',
+      birthDate: '950101',
+      birthDateCheckDigit: '6',
+      sex: 'female',
+      expirationDate: '280313',
+      expirationDateCheckDigit: '5',
+      nationality: 'FIN',
+      optional1: '010195 112X',
+      optional2: '',
+      compositeCheckDigit: '7',
+      lastName: 'SPECIMEN TRAVEL',
+      firstName: 'VILMA SOFIA',
+    });
+
+    const optional1Details = result.details.find(
+      (f) => f.field === 'optional1',
+    );
+
+    expect(optional1Details).toMatchObject({
+      value: '010195 112X',
+      line: 0,
+      start: 15,
+      end: 26,
+    });
+  });
+
   it('Utopia example', () => {
     const MRZ = [
       'I<UTOD231458907ABC<<<<<<<<<<<<',
@@ -107,8 +293,8 @@ describe('parse TD1', () => {
 
   it('parse document number', () => {
     const MRZ = [
-      'I<UTOD23145890<1240<XYZ<<<<<<<',
-      '7408122F1204159UTO<<<<<<<<<<<8',
+      'I<UTOD23145890<1233<<<<<<<<<<<',
+      '7408122F1204159UTO<<<<<<<<<<<2',
       'ERIKSSON<<ANNA<MARIA<<<<<<<<<<',
     ];
 
@@ -129,20 +315,73 @@ describe('parse TD1', () => {
     expect(documentNumberDetails).toStrictEqual({
       label: 'Document number',
       field: 'documentNumber',
-      value: 'D23145890124',
+      value: 'D23145890123',
+      valid: true,
+      ranges: [
+        { line: 0, start: 5, end: 14, raw: 'D23145890' },
+        { line: 0, start: 14, end: 15, raw: '<' },
+        { line: 0, start: 15, end: 30, raw: '1233<<<<<<<<<<<' },
+      ],
+      line: 0,
+      start: 5,
+      end: 18,
+      autocorrect: [],
+    });
+    expect(result.fields.documentNumber).toBe('D23145890123');
+    expect(result.fields.documentNumberCheckDigit).toBe('3');
+
+    const documentNumberCheckDigitDetails = result.details.find(
+      (d) => d.field === 'documentNumberCheckDigit',
+    );
+
+    expect(documentNumberCheckDigitDetails).toMatchObject({
+      line: 0,
+      start: 18,
+      end: 19,
+      value: '3',
+    });
+  });
+
+  it('parse document number ICAO Doc 9303 Sample', () => {
+    // source: https://www.icao.int/sites/default/files/publications/DocSeries/9303_p11_cons_en.pdf
+    // page 88, D.2 DERIVATION OF DOCUMENT BASIC ACCESS KEYS
+    const MRZ = [
+      'I<UTOD23145890<7349<<<<<<<<<<<',
+      '3407127M9507122UTO<<<<<<<<<<<2',
+      'STEVENSON<<PETER<JOHN<<<<<<<<<',
+    ];
+
+    const result = parse(MRZ);
+
+    expect(result).toMatchObject({
+      format: 'TD1',
+      valid: false,
+      documentNumber: result.fields.documentNumber,
+    });
+
+    expect(result.details.filter((f) => !f.valid)).toHaveLength(2);
+
+    const documentNumberDetails = result.details.find(
+      (d) => d.field === 'documentNumber',
+    );
+
+    expect(documentNumberDetails).toStrictEqual({
+      label: 'Document number',
+      field: 'documentNumber',
+      value: 'D23145890734',
       valid: true,
       ranges: [
         { line: 0, start: 5, end: 14, raw: 'D23145890' },
         { line: 0, start: 14, end: 15, raw: '<' },
-        { line: 0, start: 15, end: 30, raw: '1240<XYZ<<<<<<<' },
+        { line: 0, start: 15, end: 30, raw: '7349<<<<<<<<<<<' },
       ],
       line: 0,
       start: 5,
       end: 18,
       autocorrect: [],
     });
-    expect(result.fields.documentNumber).toBe('D23145890124');
-    expect(result.fields.documentNumberCheckDigit).toBe('0');
+    expect(result.fields.documentNumber).toBe('D23145890734');
+    expect(result.fields.documentNumberCheckDigit).toBe('9');
 
     const documentNumberCheckDigitDetails = result.details.find(
       (d) => d.field === 'documentNumberCheckDigit',
@@ -152,7 +391,7 @@ describe('parse TD1', () => {
       line: 0,
       start: 18,
       end: 19,
-      value: '0',
+      value: '9',
     });
   });
 
diff --git a/src/parsers/__tests__/check.test.ts b/src/parsers/__tests__/check.test.ts
index 0d7b821..7736722 100644
--- a/src/parsers/__tests__/check.test.ts
+++ b/src/parsers/__tests__/check.test.ts
@@ -5,5 +5,9 @@ import { check } from '../check.ts';
 test('check digits', () => {
   expect(() => check('592166117<231', 8)).not.toThrow();
   expect(() => check('592166111<773', 5)).not.toThrow();
+  expect(() => check('007666667<ZZ0', 0)).not.toThrow();
+  expect(() => check('007666667ZZ0', 0)).not.toThrow();
+  expect(() => check('007777779ZZ9', 2)).not.toThrow();
+  expect(() => check('600001795015', 2)).not.toThrow();
   expect(() => check('592166111<773', 4)).toThrow(/invalid check digit/);
 });
diff --git a/src/parsers/parseDocumentNumberCheckDigit.ts b/src/parsers/parseDocumentNumberCheckDigit.ts
index ffb351b..6894e4f 100644
--- a/src/parsers/parseDocumentNumberCheckDigit.ts
+++ b/src/parsers/parseDocumentNumberCheckDigit.ts
@@ -8,7 +8,7 @@ export default function parseDocumentNumberCheckDigit(
   if (checkDigit === '<' && optional) {
     const firstFiller = optional.indexOf('<');
     const tail = optional.slice(0, firstFiller - 1);
-    source = `${source}<${tail}`;
+    source = `${source}${tail}`;
     checkDigit = optional.charAt(firstFiller - 1);
     check(source, checkDigit);
     return {