diff --git a/itext.tests/itext.sign.tests/itext/signatures/PdfSignerUnitTest.cs b/itext.tests/itext.sign.tests/itext/signatures/PdfSignerUnitTest.cs
index 9a522a0750..b5589f8625 100644
--- a/itext.tests/itext.sign.tests/itext/signatures/PdfSignerUnitTest.cs
+++ b/itext.tests/itext.sign.tests/itext/signatures/PdfSignerUnitTest.cs
@@ -115,6 +115,34 @@ public virtual void SignWithFieldLockNotNullTest() {
             NUnit.Framework.Assert.IsTrue(signer.closed);
         }
 
+        [NUnit.Framework.Test]
+        public virtual void SignWithFieldLockNotNullAndLocksWholeDocumentTest()
+        {
+            PdfSigner signer = new PdfSigner(new PdfReader(new MemoryStream(CreateSimpleDocument(PdfVersion.PDF_2_0)))
+                , new ByteArrayOutputStream(), new StampingProperties());
+            signer.cryptoDictionary = new PdfSignature();
+            signer.appearance.SetPageRect(new Rectangle(100, 100, 10, 10));
+            var documentLocker = new PdfSigFieldLock().SetDocumentPermissions(PdfSigFieldLock.LockPermissions.NO_CHANGES_ALLOWED).SetFieldLock(PdfSigFieldLock.LockAction.ALL);
+            signer.SetFieldLockDict(documentLocker);
+            IExternalSignature pks = new PrivateKeySignature(pk, DigestAlgorithms.SHA256);
+            signer.SignDetached(pks, chain, null, null, null, 0, PdfSigner.CryptoStandard.CADES);
+            NUnit.Framework.Assert.IsTrue(signer.closed);
+        }
+
+        [NUnit.Framework.Test]
+        public virtual void SignWithFieldLockNotNullAndLocksFieldTest()
+        {
+            PdfSigner signer = new PdfSigner(new PdfReader(new MemoryStream(CreateSimpleDocument(PdfVersion.PDF_2_0)))
+                , new ByteArrayOutputStream(), new StampingProperties());
+            signer.cryptoDictionary = new PdfSignature();
+            signer.appearance.SetPageRect(new Rectangle(100, 100, 10, 10));
+            var documentLocker = new PdfSigFieldLock().SetFieldLock(PdfSigFieldLock.LockAction.ALL);
+            signer.SetFieldLockDict(documentLocker);
+            IExternalSignature pks = new PrivateKeySignature(pk, DigestAlgorithms.SHA256);
+            signer.SignDetached(pks, chain, null, null, null, 0, PdfSigner.CryptoStandard.CADES);
+            NUnit.Framework.Assert.IsTrue(signer.closed);
+        }
+
         [NUnit.Framework.Test]
         public virtual void SignDetachedWhenAlreadySignedIsNotPossibleTest() {
             PdfSigner signer = new PdfSigner(new PdfReader(new MemoryStream(CreateSimpleDocument())), new ByteArrayOutputStream
diff --git a/itext/itext.sign/itext/signatures/PdfSigner.cs b/itext/itext.sign/itext/signatures/PdfSigner.cs
index 31231e4f10..e189347c67 100644
--- a/itext/itext.sign/itext/signatures/PdfSigner.cs
+++ b/itext/itext.sign/itext/signatures/PdfSigner.cs
@@ -742,8 +742,10 @@ protected internal virtual void PreClose(IDictionary<PdfName, int?> exclusionSiz
             if (certificationLevel > 0) {
                 AddDocMDP(cryptoDictionary);
             }
-            if (fieldLock != null) {
+            if (fieldLock != null)
+            {
                 AddFieldMDP(cryptoDictionary, fieldLock);
+                LockWholeDocument(fieldLock);
             }
             if (signatureEvent != null) {
                 signatureEvent.GetSignatureDictionary(cryptoDictionary);
@@ -814,6 +816,40 @@ protected internal virtual void PreClose(IDictionary<PdfName, int?> exclusionSiz
             }
         }
 
+        /// <summary>Adds keys to the signature dictionary that define the document permissions.</summary>
+        /// <remarks>
+        /// Adds keys to the signature dictionary that define the field permissions.
+        /// This method is only used for signatures that lock the entire document.
+        /// </remarks> 
+        /// <param name="fieldLock"></param>
+        /// the
+        /// <see cref="iText.Forms.PdfSigFieldLock"/>
+        /// instance specified the field lock to be set
+        /// </param>
+        protected internal virtual void LockWholeDocument(PdfSigFieldLock fieldLock)
+        {
+            PdfDictionary pdfObject = fieldLock.GetPdfObject();
+
+            if (pdfObject.ContainsKey(PdfName.P))
+            {
+                if (pdfObject.ContainsKey(PdfName.Fields))
+                {
+                    pdfObject.Remove(PdfName.Fields);
+                }
+                if (pdfObject.ContainsKey(PdfName.Action))
+                {
+                    pdfObject.Remove(PdfName.Action);
+                }
+                if (pdfObject.ContainsKey(PdfName.All))
+                {
+                    pdfObject.Remove(PdfName.All);
+                }
+
+                document.GetCatalog().Put(PdfName.Action, pdfObject);
+                document.GetCatalog().SetModified();
+            }
+        }
+
         /// <summary>Populates already existing signature form field in the acroForm object.</summary>
         /// <remarks>
         /// Populates already existing signature form field in the acroForm object.