diff --git a/PdfForQtLib/sources/pdfdocumentbuilder.cpp b/PdfForQtLib/sources/pdfdocumentbuilder.cpp
index c0106ba..7f099b6 100644
--- a/PdfForQtLib/sources/pdfdocumentbuilder.cpp
+++ b/PdfForQtLib/sources/pdfdocumentbuilder.cpp
@@ -20,6 +20,7 @@
 #include "pdfconstants.h"
 #include "pdfdocumentreader.h"
 #include "pdfobjectutils.h"
+#include "pdfnametreeloader.h"
 
 #include <QBuffer>
 #include <QPainter>
@@ -798,6 +799,80 @@ void PDFDocumentBuilder::createDocumentParts(const std::vector<size_t>& parts)
     mergeTo(root, objectFactory.takeObject());
 }
 
+void PDFDocumentBuilder::mergeNames(PDFObjectReference a, PDFObjectReference b)
+{
+    PDFObject aObject = getObjectByReference(a);
+
+    // First object is null, do nothing
+    if (aObject.isNull())
+    {
+        setObject(a, getObjectByReference(b));
+        return;
+    }
+
+    // Jakub Melka: otherwise we must merge names tree
+    PDFObject bObject = getObjectByReference(b);
+    const PDFDictionary* aDict = getDictionaryFromObject(aObject);
+    const PDFDictionary* bDict = getDictionaryFromObject(bObject);
+
+    // Store keys
+    std::set<QByteArray> keys;
+    for (size_t i = 0; i < aDict->getCount(); ++i)
+    {
+        keys.insert(aDict->getKey(i).getString());
+    }
+    for (size_t i = 0; i < bDict->getCount(); ++i)
+    {
+        keys.insert(bDict->getKey(i).getString());
+    }
+
+    PDFObjectFactory factory;
+    factory.beginDictionary();
+
+    for (const QByteArray& key : keys)
+    {
+        auto getObject = [](const PDFObjectStorage*, const PDFObject& object) { return object; };
+        auto aMap = PDFNameTreeLoader<PDFObject>::parse(&m_storage, aDict->get(key), getObject);
+        auto bMap = PDFNameTreeLoader<PDFObject>::parse(&m_storage, bDict->get(key), getObject);
+        aMap.merge(qMove(bMap));
+
+        if (aMap.empty())
+        {
+            continue;
+        }
+
+        factory.beginDictionaryItem(key);
+        factory.beginDictionary();
+
+        factory.beginDictionaryItem("Names");
+        factory.beginArray();
+
+        for (const auto& item : aMap)
+        {
+            factory << WrapName(item.first);
+            factory << item.second;
+        }
+
+        factory.endArray();
+        factory.endDictionaryItem();
+
+        factory.beginDictionaryItem("Limits");
+        factory.beginArray();
+
+        factory << WrapName((*aMap.begin()).first);
+        factory << WrapName((*aMap.rbegin()).first);
+
+        factory.endArray();
+        factory.endDictionaryItem();
+
+        factory.endDictionary();
+        factory.endDictionaryItem();
+    }
+
+    factory.endDictionary();
+    setObject(a, factory.takeObject());
+}
+
 void PDFDocumentBuilder::appendTo(PDFObjectReference reference, PDFObject object)
 {
     m_storage.setObject(reference, PDFObjectManipulator::merge(m_storage.getObject(reference), qMove(object), PDFObjectManipulator::ConcatenateArrays));
@@ -3458,6 +3533,20 @@ void PDFDocumentBuilder::updateTrailerDictionary(PDFInteger objectCount)
 }
 
 
+void PDFDocumentBuilder::setCatalogNames(PDFObjectReference names)
+{
+    PDFObjectFactory objectBuilder;
+
+    objectBuilder.beginDictionary();
+    objectBuilder.beginDictionaryItem("Names");
+    objectBuilder << ((names.isValid()) ? PDFObject::createReference(names) : PDFObject());
+    objectBuilder.endDictionaryItem();
+    objectBuilder.endDictionary();
+    PDFObject updatedCatalog = objectBuilder.takeObject();
+    mergeTo(getCatalogReference(), updatedCatalog);
+}
+
+
 /* END GENERATED CODE */
 
 }   // namespace pdf
diff --git a/PdfForQtLib/sources/pdfdocumentbuilder.h b/PdfForQtLib/sources/pdfdocumentbuilder.h
index 599dcdb..dd80d59 100644
--- a/PdfForQtLib/sources/pdfdocumentbuilder.h
+++ b/PdfForQtLib/sources/pdfdocumentbuilder.h
@@ -354,6 +354,12 @@ public:
     /// \param parts Parts (page count of each document part)
     void createDocumentParts(const std::vector<size_t>& parts);
 
+    /// Merges two independent 'Names' entry in catalog dictionary. It is used,
+    /// for example, when documents are being merged.
+    /// \param a First 'Names' entry
+    /// \param b Second 'Names' entry
+    void mergeNames(PDFObjectReference a, PDFObjectReference b);
+
 /* START GENERATED CODE */
 
     /// Appends a new page after last page.
@@ -1082,6 +1088,11 @@ public:
     void updateTrailerDictionary(PDFInteger objectCount);
 
 
+    /// Set reference to 'Names' dictionary to catalog.
+    /// \param names Reference to Names dictionary.
+    void setCatalogNames(PDFObjectReference names);
+
+
 /* END GENERATED CODE */
 
 private:
diff --git a/PdfTool/pdftoolunite.cpp b/PdfTool/pdftoolunite.cpp
index edaa964..b097658 100644
--- a/PdfTool/pdftoolunite.cpp
+++ b/PdfTool/pdftoolunite.cpp
@@ -74,6 +74,7 @@ int PDFToolUnite::execute(const PDFToolOptions& options)
 
         pdf::PDFObjectReference ocPropertiesMerged = documentBuilder.addObject(pdf::PDFObject());
         pdf::PDFObjectReference formMerged = documentBuilder.addObject(pdf::PDFObject());
+        pdf::PDFObjectReference namesMerged = documentBuilder.addObject(pdf::PDFObject());
 
         std::vector<pdf::PDFObjectReference> pages;
         for (const QString& fileName : files)
@@ -161,6 +162,7 @@ int PDFToolUnite::execute(const PDFToolOptions& options)
 
             documentBuilder.appendTo(ocPropertiesMerged, documentBuilder.getObjectByReference(ocPropertiesReference));
             documentBuilder.appendTo(formMerged, documentBuilder.getObjectByReference(acroFormReference));
+            documentBuilder.mergeNames(namesMerged, namesReference);
             pages.insert(pages.end(), references.cbegin(), references.cend());
         }
 
@@ -170,6 +172,11 @@ int PDFToolUnite::execute(const PDFToolOptions& options)
             documentBuilder.setCatalogOptionalContentProperties(ocPropertiesMerged);
         }
 
+        if (!documentBuilder.getObjectByReference(namesMerged).isNull())
+        {
+            documentBuilder.setCatalogNames(namesMerged);
+        }
+
         if (!documentBuilder.getObjectByReference(formMerged).isNull())
         {
             documentBuilder.setCatalogAcroForm(formMerged);
diff --git a/generated_code_definition.xml b/generated_code_definition.xml
index c4fa34e..d6e56a6 100644
--- a/generated_code_definition.xml
+++ b/generated_code_definition.xml
@@ -7859,5 +7859,62 @@ updateDocumentInfo(qMove(updatedInfoDictionary));</property>
       <property name="functionDescription">This function is used to update trailer dictionary. Must be called each time the final document is being built.</property>
       <property name="returnType">_void</property>
     </QObject>
+    <QObject class="codegen::GeneratedFunction">
+      <property name="objectName"></property>
+      <property name="items">
+        <QObject class="codegen::GeneratedAction">
+          <property name="objectName"></property>
+          <property name="items">
+            <QObject class="codegen::GeneratedParameter">
+              <property name="objectName"></property>
+              <property name="items"/>
+              <property name="parameterName">names</property>
+              <property name="parameterType">_PDFObjectReference</property>
+              <property name="parameterDescription">Reference to Names dictionary.</property>
+            </QObject>
+          </property>
+          <property name="actionType">Parameters</property>
+          <property name="variableName"></property>
+          <property name="variableType">_void</property>
+          <property name="code"></property>
+        </QObject>
+        <QObject class="codegen::GeneratedAction">
+          <property name="objectName"></property>
+          <property name="items">
+            <QObject class="codegen::GeneratedPDFObject">
+              <property name="objectName"></property>
+              <property name="items">
+                <QObject class="codegen::GeneratedPDFObject">
+                  <property name="objectName"></property>
+                  <property name="items"/>
+                  <property name="dictionaryItemName">Names</property>
+                  <property name="objectType">DictionaryItemSimple</property>
+                  <property name="value">((names.isValid()) ? PDFObject::createReference(names) : PDFObject())</property>
+                </QObject>
+              </property>
+              <property name="dictionaryItemName"></property>
+              <property name="objectType">Dictionary</property>
+              <property name="value"></property>
+            </QObject>
+          </property>
+          <property name="actionType">CreateObject</property>
+          <property name="variableName">updatedCatalog</property>
+          <property name="variableType">_PDFObject</property>
+          <property name="code"></property>
+        </QObject>
+        <QObject class="codegen::GeneratedAction">
+          <property name="objectName"></property>
+          <property name="items"/>
+          <property name="actionType">Code</property>
+          <property name="variableName"></property>
+          <property name="variableType">_void</property>
+          <property name="code">mergeTo(getCatalogReference(), updatedCatalog);</property>
+        </QObject>
+      </property>
+      <property name="functionType">Structure</property>
+      <property name="functionName">setCatalogNames</property>
+      <property name="functionDescription">Set reference to 'Names' dictionary to catalog.</property>
+      <property name="returnType">_void</property>
+    </QObject>
   </property>
 </root>