diff --git a/flips-gtk.cpp b/flips-gtk.cpp
index 72c70a7..fb86493 100644
--- a/flips-gtk.cpp
+++ b/flips-gtk.cpp
@@ -356,7 +356,7 @@ static void ApplyPatchMultiAutoSub(gpointer data, gpointer user_data)
 	gchar * outrompath=g_strndup(patchpath, strlen(patchpath)+strlen(romext)+1);
 	strcpy(GetExtension(outrompath), romext);
 	
-	struct errorinfo errinf=ApplyPatchMem(patch, rompath, true, outrompath, NULL, true);
+	struct errorinfo errinf=ApplyPatchMem(patch, rompath, !cfg.getint("skipchecksum"), outrompath, NULL, true);
 	if (errinf.level==el_broken) error(ea_invalid);
 	if (errinf.level==el_notthis) error(ea_no_auto);
 	if (errinf.level==el_warning) error(ea_warning);
@@ -433,7 +433,7 @@ static void ApplyPatchMulti(gpointer data, gpointer user_data)
 		char * outromext=GetExtension(outromname);
 		strcpy(outromext, state->romext);
 		
-		struct errorinfo errinf=ApplyPatchMem2(patch, state->rommem, state->removeHeaders, true, outromname, NULL);
+		struct errorinfo errinf=ApplyPatchMem2(patch, state->rommem, state->removeHeaders, !cfg.getint("skipchecksum"), outromname, NULL);
 		if (errinf.level==el_broken) error(e_invalid);
 		if (errinf.level==el_notthis) error(e_invalid_this);
 		if (errinf.level==el_warning) error(e_warning);
@@ -486,7 +486,7 @@ static void a_ApplyPatch(GtkButton* widget, gpointer user_data)
 		char * outromname=SelectRom(outromname_d, "Select Output File", true);
 		if (outromname)
 		{
-			struct errorinfo errinf=ApplyPatchMem(patchfile, inromname, true, outromname, NULL, cfg.getint("autorom"));
+			struct errorinfo errinf=ApplyPatchMem(patchfile, inromname, !cfg.getint("skipchecksum"), outromname, NULL, cfg.getint("autorom"));
 			ShowMessage(errinf);
 		}
 		g_free(inromname);
@@ -596,43 +596,8 @@ static void a_CreatePatch(GtkButton* widget, gpointer user_data)
 			gtk_file_filter_add_pattern(filter, typeinfo[i].filter);
 			gtk_file_chooser_add_filter(GTK_FILE_CHOOSER(dialog), filter);
 		}
-		gtk_file_chooser_set_filter(GTK_FILE_CHOOSER(dialog), filters[lasttype-1]);
-		
-		struct wrap {
-			GtkFileChooser* chooser;
-			GtkFileFilter** filters;
-			int current_filter_id;
-			
-			void notify(GObject* self, GParamSpec* pspec)
-			{
-				GtkFileFilter* filter = gtk_file_chooser_get_filter(chooser);
-				int new_filter_id = 0;
-				while (filter != filters[new_filter_id])
-					new_filter_id++;
-				
-				const char * prev_ext = typeinfo[current_filter_id].filter+1;
-				const char * new_ext = typeinfo[new_filter_id].filter+1;
-				
-				char * current_name = gtk_file_chooser_get_current_name(chooser);
-				char * current_name_ext = strrchr(current_name, '.');
-				if (!strcmp(current_name_ext, prev_ext))
-				{
-					// good thing they're all the same length
-					strcpy(current_name_ext, new_ext);
-					gtk_file_chooser_set_current_name(chooser, current_name);
-				}
-				
-				g_free(current_name);
-				current_filter_id = new_filter_id;
-			}
-			static void notify_s(GObject* self, GParamSpec* pspec, void* userdata)
-			{
-				((wrap*)userdata)->notify(self, pspec);
-			}
-		};
-		wrap filter_updater = { GTK_FILE_CHOOSER(dialog), filters, lasttype-1 };
-		g_signal_connect(dialog, "notify::filter", G_CALLBACK(&wrap::notify_s), &filter_updater);
 		
+		gtk_file_chooser_set_filter(GTK_FILE_CHOOSER(dialog), filters[lasttype-1]);
 		if (gtk_dialog_run(GTK_DIALOG(dialog))==GTK_RESPONSE_ACCEPT)
 		{
 			patchname=gtk_file_chooser_get_uri(GTK_FILE_CHOOSER(dialog));
@@ -643,8 +608,11 @@ static void a_CreatePatch(GtkButton* widget, gpointer user_data)
 		{
 			if (filter==filters[i])
 			{
+				if (patchname && lasttype!=i && !strcmp(GetExtension(patchname), typeinfo[lasttype-1].filter+1))
+				{
+					strcpy(GetExtension(patchname), typeinfo[i].filter+1);
+				}
 				cfg.setint("lasttype", i+1);
-				lasttype = i+1;
 			}
 		}
 		
@@ -709,7 +677,7 @@ static void a_ApplyRun(GtkButton* widget, gpointer user_data)
 	else outromname=g_file_get_uri(outrom_file);
 	g_object_unref(outrom_file);
 	
-	struct errorinfo errinf=ApplyPatchMem(patchfile, romname, true, outromname, NULL, cfg.getint("autorom"));
+	struct errorinfo errinf=ApplyPatchMem(patchfile, romname, !cfg.getint("skipchecksum"), outromname, NULL, cfg.getint("autorom"));
 	if (errinf.level!=el_ok) ShowMessage(errinf);
 	if (errinf.level>=el_notthis) goto cleanup;
 	
@@ -795,6 +763,13 @@ static void a_ShowSettings(GtkButton* widget, gpointer user_data)
 	gtk_grid_attach(grid, autoRom, 0,3, 1,1);
 	flatpakDisable(autoRom);
 	
+	GtkWidget* skipChecksum;
+	skipChecksum=gtk_check_button_new_with_mnemonic("Ignore checksum when patching");
+	if (cfg.getint("skipchecksum")) gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(skipChecksum), true);
+	g_object_ref(skipChecksum);
+	gtk_grid_attach(grid, skipChecksum, 0,4, 1,1);
+	flatpakDisable(skipChecksum);
+	
 	gtk_container_add(GTK_CONTAINER(settingswindow), GTK_WIDGET(grid));
 	
 	gtk_widget_show_all(settingswindow);
@@ -802,8 +777,10 @@ static void a_ShowSettings(GtkButton* widget, gpointer user_data)
 	
 	cfg.setint("assocemu", (gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(emuAssoc))));
 	cfg.setint("autorom", (gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(autoRom))));
+	cfg.setint("skipchecksum", (gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(skipChecksum))));
 	g_object_unref(emuAssoc);
 	g_object_unref(autoRom);
+	g_object_unref(skipChecksum);
 }
 
 static gboolean filterExecOnly(const GtkFileFilterInfo* filter_info, gpointer data)