diff --git a/include/qpdf/QPDFAcroFormDocumentHelper.hh b/include/qpdf/QPDFAcroFormDocumentHelper.hh
index 6094ed7..0ac2313 100644
--- a/include/qpdf/QPDFAcroFormDocumentHelper.hh
+++ b/include/qpdf/QPDFAcroFormDocumentHelper.hh
@@ -241,23 +241,7 @@ class QPDFAcroFormDocumentHelper: public QPDFDocumentHelper
     void adjustAppearanceStream(
         QPDFObjectHandle stream, std::map<std::string, std::map<std::string, std::string>> dr_map);
 
-    class Members
-    {
-        friend class QPDFAcroFormDocumentHelper;
-
-      public:
-        ~Members() = default;
-
-      private:
-        Members() = default;
-        Members(Members const&) = delete;
-
-        bool cache_valid{false};
-        std::map<QPDFObjGen, std::vector<QPDFAnnotationObjectHelper>> field_to_annotations;
-        std::map<QPDFObjGen, QPDFFormFieldObjectHelper> annotation_to_field;
-        std::map<QPDFObjGen, std::string> field_to_name;
-        std::map<std::string, std::set<QPDFObjGen>> name_to_fields;
-    };
+    class Members;
 
     std::shared_ptr<Members> m;
 };
diff --git a/libqpdf/QPDFAcroFormDocumentHelper.cc b/libqpdf/QPDFAcroFormDocumentHelper.cc
index 6974133..e3a0c95 100644
--- a/libqpdf/QPDFAcroFormDocumentHelper.cc
+++ b/libqpdf/QPDFAcroFormDocumentHelper.cc
@@ -13,9 +13,23 @@
 using namespace qpdf;
 using namespace std::literals;
 
+class QPDFAcroFormDocumentHelper::Members
+{
+  public:
+    Members() = default;
+    Members(Members const&) = delete;
+    ~Members() = default;
+
+    bool cache_valid{false};
+    std::map<QPDFObjGen, std::vector<QPDFAnnotationObjectHelper>> field_to_annotations;
+    std::map<QPDFObjGen, QPDFFormFieldObjectHelper> annotation_to_field;
+    std::map<QPDFObjGen, std::string> field_to_name;
+    std::map<std::string, std::set<QPDFObjGen>> name_to_fields;
+};
+
 QPDFAcroFormDocumentHelper::QPDFAcroFormDocumentHelper(QPDF& qpdf) :
     QPDFDocumentHelper(qpdf),
-    m(new Members())
+    m(std::make_shared<Members>())
 {
     // We have to analyze up front. Otherwise, when we are adding annotations and fields, we are in
     // a temporarily unstable configuration where some widget annotations are not reachable.