diff --git a/include/wx/fs_mem.h b/include/wx/fs_mem.h
index 9e6e126bb2..6a40ae1a7b 100644
--- a/include/wx/fs_mem.h
+++ b/include/wx/fs_mem.h
@@ -15,10 +15,10 @@
 
 #include "wx/filesys.h"
 
-#include "wx/hashmap.h"
+#include <memory>
+#include <unordered_map>
 
 class wxMemoryFSFile;
-WX_DECLARE_STRING_HASH_MAP(wxMemoryFSFile *, wxMemoryFSHash);
 
 #if wxUSE_GUI
     #include "wx/bitmap.h"
@@ -59,7 +59,13 @@ protected:
     // error and returns false if it does exist
     static bool CheckDoesntExist(const wxString& filename);
 
+    // add the given object to m_Hash, taking ownership of the pointer
+    static void DoAddFile(const wxString& filename, wxMemoryFSFile* file);
+
+private:
     // the hash map indexed by the names of the files stored in the memory FS
+    using wxMemoryFSHash =
+        std::unordered_map<wxString, std::unique_ptr<wxMemoryFSFile>>;
     static wxMemoryFSHash m_Hash;
 
     // the file name currently being searched for, i.e. the argument of the
diff --git a/src/common/fs_mem.cpp b/src/common/fs_mem.cpp
index f4e943b941..08fbed97c1 100644
--- a/src/common/fs_mem.cpp
+++ b/src/common/fs_mem.cpp
@@ -77,7 +77,7 @@ private:
 //--------------------------------------------------------------------------------
 
 
-wxMemoryFSHash wxMemoryFSHandlerBase::m_Hash;
+wxMemoryFSHandlerBase::wxMemoryFSHash wxMemoryFSHandlerBase::m_Hash;
 
 
 wxMemoryFSHandlerBase::wxMemoryFSHandlerBase() : wxFileSystemHandler()
@@ -89,7 +89,6 @@ wxMemoryFSHandlerBase::~wxMemoryFSHandlerBase()
     // as only one copy of FS handler is supposed to exist, we may silently
     // delete static data here. (There is no way how to remove FS handler from
     // wxFileSystem other than releasing _all_ handlers.)
-    WX_CLEAR_HASH_MAP(wxMemoryFSHash, m_Hash);
 }
 
 bool wxMemoryFSHandlerBase::CanOpen(const wxString& location)
@@ -104,7 +103,7 @@ wxFSFile * wxMemoryFSHandlerBase::OpenFile(wxFileSystem& WXUNUSED(fs),
     if ( i == m_Hash.end() )
         return nullptr;
 
-    const wxMemoryFSFile * const obj = i->second;
+    const auto& obj = i->second;
 
     return new wxFSFile
                (
@@ -175,6 +174,13 @@ bool wxMemoryFSHandlerBase::CheckDoesntExist(const wxString& filename)
 }
 
 
+/*static*/
+void wxMemoryFSHandlerBase::DoAddFile(const wxString& filename,
+                                      wxMemoryFSFile* file)
+{
+    m_Hash[filename] = std::unique_ptr<wxMemoryFSFile>(file);
+}
+
 /*static*/
 void wxMemoryFSHandlerBase::AddFileWithMimeType(const wxString& filename,
                                                 const wxString& textdata,
@@ -199,7 +205,7 @@ void wxMemoryFSHandlerBase::AddFileWithMimeType(const wxString& filename,
     if ( !CheckDoesntExist(filename) )
         return;
 
-    m_Hash[filename] = new wxMemoryFSFile(binarydata, size, mimetype);
+    DoAddFile(filename, new wxMemoryFSFile(binarydata, size, mimetype));
 }
 
 /*static*/
@@ -221,17 +227,12 @@ void wxMemoryFSHandlerBase::AddFile(const wxString& filename,
 
 /*static*/ void wxMemoryFSHandlerBase::RemoveFile(const wxString& filename)
 {
-    wxMemoryFSHash::iterator i = m_Hash.find(filename);
-    if ( i == m_Hash.end() )
+    if ( !m_Hash.erase(filename) )
     {
         wxLogError(_("Trying to remove file '%s' from memory VFS, "
                      "but it is not loaded!"),
                    filename);
-        return;
     }
-
-    delete i->second;
-    m_Hash.erase(i);
 }
 
 #endif // wxUSE_BASE
@@ -250,11 +251,11 @@ wxMemoryFSHandler::AddFile(const wxString& filename,
     wxMemoryOutputStream mems;
     if ( image.IsOk() && image.SaveFile(mems, type) )
     {
-        m_Hash[filename] = new wxMemoryFSFile
-                               (
+        DoAddFile(filename, new wxMemoryFSFile
+                                (
                                     mems,
                                     wxImage::FindHandler(type)->GetMimeType()
-                               );
+                                ));
     }
     else
     {