diff --git a/include/qpdf/Buffer.hh b/include/qpdf/Buffer.hh
index 7fdc5c4..40d1b59 100644
--- a/include/qpdf/Buffer.hh
+++ b/include/qpdf/Buffer.hh
@@ -23,7 +23,7 @@
 #define BUFFER_HH
 
 #include <qpdf/DLL.h>
-#include <qpdf/PointerHolder.hh>
+#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
 
 #include <memory>
 #include <stddef.h>
diff --git a/include/qpdf/ClosedFileInputSource.hh b/include/qpdf/ClosedFileInputSource.hh
index b23c276..58c78f7 100644
--- a/include/qpdf/ClosedFileInputSource.hh
+++ b/include/qpdf/ClosedFileInputSource.hh
@@ -29,7 +29,7 @@
 // file descriptors. This is used for merging large numbers of files.
 
 #include <qpdf/InputSource.hh>
-#include <qpdf/PointerHolder.hh>
+#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
 
 #include <memory>
 
diff --git a/include/qpdf/InputSource.hh b/include/qpdf/InputSource.hh
index 56a3782..aa79d53 100644
--- a/include/qpdf/InputSource.hh
+++ b/include/qpdf/InputSource.hh
@@ -23,7 +23,7 @@
 #define QPDF_INPUTSOURCE_HH
 
 #include <qpdf/DLL.h>
-#include <qpdf/PointerHolder.hh>
+#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
 #include <qpdf/Types.h>
 
 #include <memory>
diff --git a/include/qpdf/JSON.hh b/include/qpdf/JSON.hh
index 554823e..77c4b10 100644
--- a/include/qpdf/JSON.hh
+++ b/include/qpdf/JSON.hh
@@ -36,7 +36,7 @@
 // general-purpose JSON package.
 
 #include <qpdf/DLL.h>
-#include <qpdf/PointerHolder.hh>
+#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
 #include <qpdf/Types.h>
 
 #include <functional>
diff --git a/include/qpdf/Pipeline.hh b/include/qpdf/Pipeline.hh
index d5d48bd..7a0d002 100644
--- a/include/qpdf/Pipeline.hh
+++ b/include/qpdf/Pipeline.hh
@@ -45,7 +45,7 @@
 #define PIPELINE_HH
 
 #include <qpdf/DLL.h>
-#include <qpdf/PointerHolder.hh>
+#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
 
 #include <memory>
 #include <string>
diff --git a/include/qpdf/Pl_Buffer.hh b/include/qpdf/Pl_Buffer.hh
index ed9056a..6f7bb96 100644
--- a/include/qpdf/Pl_Buffer.hh
+++ b/include/qpdf/Pl_Buffer.hh
@@ -35,6 +35,7 @@
 
 #include <qpdf/Buffer.hh>
 #include <qpdf/Pipeline.hh>
+#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
 
 #include <memory>
 
diff --git a/include/qpdf/Pl_QPDFTokenizer.hh b/include/qpdf/Pl_QPDFTokenizer.hh
index 5dbaf78..12a69b4 100644
--- a/include/qpdf/Pl_QPDFTokenizer.hh
+++ b/include/qpdf/Pl_QPDFTokenizer.hh
@@ -25,7 +25,7 @@
 #include <qpdf/Pipeline.hh>
 
 #include <qpdf/Pl_Buffer.hh>
-#include <qpdf/PointerHolder.hh>
+#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
 #include <qpdf/QPDFObjectHandle.hh>
 #include <qpdf/QPDFTokenizer.hh>
 
diff --git a/include/qpdf/QPDFObjectHandle.hh b/include/qpdf/QPDFObjectHandle.hh
index 66fd4a5..6645f1c 100644
--- a/include/qpdf/QPDFObjectHandle.hh
+++ b/include/qpdf/QPDFObjectHandle.hh
@@ -36,7 +36,7 @@
 #include <qpdf/Buffer.hh>
 #include <qpdf/InputSource.hh>
 #include <qpdf/JSON.hh>
-#include <qpdf/PointerHolder.hh>
+#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
 #include <qpdf/QPDFObjGen.hh>
 #include <qpdf/QPDFTokenizer.hh>
 
diff --git a/include/qpdf/QPDFTokenizer.hh b/include/qpdf/QPDFTokenizer.hh
index 33b2e71..4727dac 100644
--- a/include/qpdf/QPDFTokenizer.hh
+++ b/include/qpdf/QPDFTokenizer.hh
@@ -25,7 +25,7 @@
 #include <qpdf/DLL.h>
 
 #include <qpdf/InputSource.hh>
-#include <qpdf/PointerHolder.hh>
+#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
 
 #include <memory>
 #include <stdio.h>
diff --git a/include/qpdf/QPDFWriter.hh b/include/qpdf/QPDFWriter.hh
index 8c076bb..040f3eb 100644
--- a/include/qpdf/QPDFWriter.hh
+++ b/include/qpdf/QPDFWriter.hh
@@ -44,7 +44,7 @@
 #include <qpdf/PDFVersion.hh>
 #include <qpdf/Pipeline.hh>
 #include <qpdf/Pl_Buffer.hh>
-#include <qpdf/PointerHolder.hh>
+#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
 #include <qpdf/QPDFObjGen.hh>
 #include <qpdf/QPDFObjectHandle.hh>
 #include <qpdf/QPDFXRefEntry.hh>
diff --git a/include/qpdf/QUtil.hh b/include/qpdf/QUtil.hh
index 96f4f7e..6d9d18a 100644
--- a/include/qpdf/QUtil.hh
+++ b/include/qpdf/QUtil.hh
@@ -23,7 +23,7 @@
 #define QUTIL_HH
 
 #include <qpdf/DLL.h>
-#include <qpdf/PointerHolder.hh>
+#include <qpdf/PointerHolder.hh> // unused -- remove in qpdf 12 (see #785)
 #include <qpdf/Types.h>
 #include <cstring>
 #include <functional>