diff --git a/src/devices/imagedev/chd_cd.cpp b/src/devices/imagedev/chd_cd.cpp
index f090d7f0032..cac16961a31 100644
--- a/src/devices/imagedev/chd_cd.cpp
+++ b/src/devices/imagedev/chd_cd.cpp
@@ -61,7 +61,7 @@ void cdrom_image_device::device_config_complete()
 {
 	m_extension_list = "chd,cue,toc,nrg,gdi,iso,cdr";
 
-	m_formatlist.push_back(std::make_unique<image_device_format>("chdcd", "CD-ROM drive", m_extension_list, cd_option_spec));
+	add_format("chdcd", "CD-ROM drive", m_extension_list, cd_option_spec);
 
 	// set brief and instance name
 	update_names();
diff --git a/src/devices/imagedev/diablo.cpp b/src/devices/imagedev/diablo.cpp
index 64e313865bf..a47451a1c47 100644
--- a/src/devices/imagedev/diablo.cpp
+++ b/src/devices/imagedev/diablo.cpp
@@ -56,7 +56,7 @@ diablo_image_device::~diablo_image_device()
 
 void diablo_image_device::device_config_complete()
 {
-	m_formatlist.push_back(std::make_unique<image_device_format>("chd", "CHD Hard drive", "chd,dsk", dsk_option_spec));
+	add_format("chd", "CHD Hard drive", "chd,dsk", dsk_option_spec);
 
 	// set brief and instance name
 	update_names();
diff --git a/src/devices/imagedev/flopdrv.cpp b/src/devices/imagedev/flopdrv.cpp
index e19340c40c9..290d6671cd3 100644
--- a/src/devices/imagedev/flopdrv.cpp
+++ b/src/devices/imagedev/flopdrv.cpp
@@ -825,7 +825,7 @@ void legacy_floppy_image_device::device_config_complete()
 		// only add if creatable
 		if (floppy_options[i].param_guidelines) {
 			// allocate a new format and append it to the list
-			m_formatlist.push_back(std::make_unique<image_device_format>(floppy_options[i].name, floppy_options[i].description, floppy_options[i].extensions, floppy_options[i].param_guidelines));
+			add_format(floppy_options[i].name, floppy_options[i].description, floppy_options[i].extensions, floppy_options[i].param_guidelines);
 		}
 		image_specify_extension( m_extension_list, 256, floppy_options[i].extensions );
 	}
diff --git a/src/devices/imagedev/floppy.cpp b/src/devices/imagedev/floppy.cpp
index 44b80e6629a..30d535c28fa 100644
--- a/src/devices/imagedev/floppy.cpp
+++ b/src/devices/imagedev/floppy.cpp
@@ -242,7 +242,7 @@ void floppy_image_device::set_formats(const floppy_format_type *formats)
 		else
 			fif_list->append(fif);
 
-		m_formatlist.push_back(std::make_unique<image_device_format>(fif->name(), fif->description(), fif->extensions(), ""));
+		add_format(fif->name(), fif->description(), fif->extensions(), "");
 
 		image_specify_extension( extension_list, 256, fif->extensions() );
 	}
diff --git a/src/devices/imagedev/harddriv.cpp b/src/devices/imagedev/harddriv.cpp
index 42eeac477be..588ef862c4d 100644
--- a/src/devices/imagedev/harddriv.cpp
+++ b/src/devices/imagedev/harddriv.cpp
@@ -79,7 +79,7 @@ harddisk_image_device::~harddisk_image_device()
 
 void harddisk_image_device::device_config_complete()
 {
-	m_formatlist.push_back(std::make_unique<image_device_format>("chd", "CHD Hard drive", "chd,hd", hd_option_spec));
+	add_format("chd", "CHD Hard drive", "chd,hd", hd_option_spec);
 
 	// set brief and instance name
 	update_names();
diff --git a/src/emu/diimage.cpp b/src/emu/diimage.cpp
index 56be4f9a6de..cb2a7f6a02d 100644
--- a/src/emu/diimage.cpp
+++ b/src/emu/diimage.cpp
@@ -237,6 +237,27 @@ const image_device_format *device_image_interface::device_get_named_creatable_fo
 }
 
 
+//-------------------------------------------------
+//  add_format
+//-------------------------------------------------
+
+void device_image_interface::add_format(std::unique_ptr<image_device_format> &&format)
+{
+	m_formatlist.push_back(std::move(format));
+}
+
+
+//-------------------------------------------------
+//  add_format
+//-------------------------------------------------
+
+void device_image_interface::add_format(std::string &&name, std::string &&description, std::string &&extensions, std::string &&optspec)
+{
+	auto format = std::make_unique<image_device_format>(std::move(name), std::move(description), std::move(extensions), std::move(optspec));
+	add_format(std::move(format));
+}
+
+
 /****************************************************************************
     ERROR HANDLING
 ****************************************************************************/
diff --git a/src/emu/diimage.h b/src/emu/diimage.h
index 009cd9bc534..7854f9022c1 100644
--- a/src/emu/diimage.h
+++ b/src/emu/diimage.h
@@ -273,6 +273,9 @@ protected:
 	bool load_software_part(const char *path, const software_part *&swpart);
 	std::string software_get_default_slot(const char *default_card_slot) const;
 
+	void add_format(std::unique_ptr<image_device_format> &&format);
+	void add_format(std::string &&name, std::string &&description, std::string &&extensions, std::string &&optspec);
+
 	// derived class overrides
 
 	// configuration
@@ -320,9 +323,6 @@ protected:
 	std::string m_brief_instance_name;
 	std::string m_instance_name;
 
-	// creation info
-	formatlist_type m_formatlist;
-
 	// in the case of arcade cabinet with fixed carts inserted,
 	// we want to disable command line cart loading...
 	bool m_user_loadable;
@@ -331,6 +331,9 @@ protected:
 
 private:
 	static image_error_t image_error_from_file_error(osd_file::error filerr);
+
+	// creation info
+	formatlist_type m_formatlist;
 };
 
 // iterator