diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index 3a96465..5c72571 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -27,9 +27,8 @@
 using namespace qpdf;
 using namespace std::literals;
 
-using QDoc = QPDF::Doc;
-using Common = QDoc::Common;
-using Objects = QDoc::Objects;
+using Common = impl::Doc::Common;
+using Objects = impl::Doc::Objects;
 using Foreign = Objects::Foreign;
 using Streams = Objects::Streams;
 
diff --git a/libqpdf/QPDFJob.cc b/libqpdf/QPDFJob.cc
index d920ab0..ddada94 100644
--- a/libqpdf/QPDFJob.cc
+++ b/libqpdf/QPDFJob.cc
@@ -30,8 +30,7 @@
 
 using namespace qpdf;
 
-using QDoc = QPDF::Doc;
-using Pages = QDoc::Pages;
+using Pages = impl::Doc::Pages;
 
 namespace
 {
diff --git a/libqpdf/QPDFWriter.cc b/libqpdf/QPDFWriter.cc
index 5c9c6e6..6a10919 100644
--- a/libqpdf/QPDFWriter.cc
+++ b/libqpdf/QPDFWriter.cc
@@ -27,8 +27,7 @@
 using namespace std::literals;
 using namespace qpdf;
 
-using QDoc = QPDF::Doc;
-using Encryption = QDoc::Encryption;
+using Encryption = impl::Doc::Encryption;
 
 QPDFWriter::ProgressReporter::~ProgressReporter() // NOLINT (modernize-use-equals-default)
 {
diff --git a/libqpdf/qpdf/QPDF_private.hh b/libqpdf/qpdf/QPDF_private.hh
index 79efe70..9f76434 100644
--- a/libqpdf/qpdf/QPDF_private.hh
+++ b/libqpdf/qpdf/QPDF_private.hh
@@ -22,6 +22,11 @@ namespace qpdf
         class OffsetBuffer;
     } // namespace is
 
+    namespace impl
+    {
+        using Doc = QPDF::Doc;
+    }
+
     class Doc: public QPDF
     {
       public: