diff --git a/gtk2_ardour/ardour_ui_session.cc b/gtk2_ardour/ardour_ui_session.cc
index 1b6c4baff7..8641e16aff 100644
--- a/gtk2_ardour/ardour_ui_session.cc
+++ b/gtk2_ardour/ardour_ui_session.cc
@@ -50,6 +50,7 @@
 
 #include "ardour/audioengine.h"
 #include "ardour/filename_extensions.h"
+#include "ardour/plugin_manager.h"
 #include "ardour/profile.h"
 #include "ardour/session.h"
 #include "ardour/session_utils.h"
@@ -62,6 +63,7 @@
 #include "missing_filesource_dialog.h"
 #include "missing_plugin_dialog.h"
 #include "opts.h"
+#include "plugin_scan_dialog.h"
 #include "public_editor.h"
 #include "save_as_dialog.h"
 #include "session_dialog.h"
@@ -480,9 +482,17 @@ ARDOUR_UI::load_session_stage_two (const std::string& path, const std::string& s
 	}
 	{
 		list<string> const u = new_session->unknown_processors ();
+		bool scan_now = false;
 		if (!u.empty()) {
-			MissingPluginDialog d (_session, u);
-			d.run ();
+			MissingPluginDialog d (_session, u, PluginManager::instance ().cache_valid ());
+			if (d.run () == RESPONSE_YES) {
+				scan_now = true;
+			}
+		}
+		if (scan_now) {
+			PluginScanDialog psd (false, true);
+			psd.start ();
+			show_plugin_manager ();
 		}
 	}
 
diff --git a/gtk2_ardour/missing_plugin_dialog.cc b/gtk2_ardour/missing_plugin_dialog.cc
index 97e7625b0c..163259721f 100644
--- a/gtk2_ardour/missing_plugin_dialog.cc
+++ b/gtk2_ardour/missing_plugin_dialog.cc
@@ -20,7 +20,10 @@
  */
 
 #include <gtkmm/label.h>
+
+#include "pbd/compose.h"
 #include "missing_plugin_dialog.h"
+
 #include "pbd/i18n.h"
 
 using namespace Gtk;
@@ -28,7 +31,7 @@ using namespace std;
 using namespace ARDOUR;
 using namespace PBD;
 
-MissingPluginDialog::MissingPluginDialog (Session * s, list<string> const & plugins)
+MissingPluginDialog::MissingPluginDialog (Session* s, list<string> const & plugins, bool cache_valid)
 	: ArdourDialog (_("Missing Plugins"), true, false)
 {
 	/* This dialog is always shown programatically. Center the window.*/
@@ -36,22 +39,34 @@ MissingPluginDialog::MissingPluginDialog (Session * s, list<string> const & plug
 
 	set_session (s);
 
-	add_button (_("OK"), RESPONSE_OK);
-	set_default_response (RESPONSE_OK);
-
-	Label* m = manage (new Label);
-
 	stringstream t;
 	t << _("This session contains the following plugins that cannot be found on this system:\n\n");
 
 	for (list<string>::const_iterator i = plugins.begin(); i != plugins.end(); ++i) {
 		t << *i << "\n";
 	}
+	t << _("\nThose plugins will be replaced with inactive stubs.\n");
 
-	t << _("\nThose plugins will be replaced with inactive stubs.\n"
-	       "It is recommended that you install the missing plugins and re-load the session.\n"
-	       "(also check the blacklist, Window > Log and Preferences > Plugins)");
+	if (cache_valid) {
+		add_button (_("OK"), RESPONSE_OK);
+		set_default_response (RESPONSE_OK);
+		t << _("It is recommended that you install the missing plugins and re-load the session.\n");
+	} else {
+    t << _("Third party plugins have not yet been indexed.\n");
+		t << string_compose (_("Scan %1 plugins now?"),
+#ifdef __APPLE__
+				_("AudioUnit and VST")
+#else
+				_("VST")
+#endif
+				);
 
+		add_button (_("Yes"), RESPONSE_YES);
+		add_button (_("No"), RESPONSE_NO);
+		set_default_response (RESPONSE_YES);
+	}
+
+	Label* m = manage (new Label);
 	m->set_markup (t.str ());
 	get_vbox()->pack_start (*m, false, false);
 
diff --git a/gtk2_ardour/missing_plugin_dialog.h b/gtk2_ardour/missing_plugin_dialog.h
index ff43275914..570e8bfe24 100644
--- a/gtk2_ardour/missing_plugin_dialog.h
+++ b/gtk2_ardour/missing_plugin_dialog.h
@@ -30,7 +30,7 @@ namespace ARDOUR {
 class MissingPluginDialog : public ArdourDialog
 {
 public:
-	MissingPluginDialog (ARDOUR::Session *, std::list<std::string> const &);
+	MissingPluginDialog (ARDOUR::Session*, std::list<std::string> const &, bool);
 };
 
 #endif /* __gtk_ardour_missing_plugin_dialog_h__ */
diff --git a/gtk2_ardour/plugin_selector.cc b/gtk2_ardour/plugin_selector.cc
index f0903d6b97..8c559eecdc 100644
--- a/gtk2_ardour/plugin_selector.cc
+++ b/gtk2_ardour/plugin_selector.cc
@@ -1237,15 +1237,22 @@ PluginSelector::show_manager ()
 #endif
 				, false, MESSAGE_QUESTION, BUTTONS_YES_NO);
 
+		q.set_title (string_compose (_("Discover %1 Plugins?"),
 #ifdef __APPLE__
-		q.set_title (_("Discover VST/AU Plugins?"));
-    q.set_secondary_text (_("Third party plugins have not yet been indexed. AudioUnit and VST plugins have to be scanned before they can be used. This can also be done manually from Preferences > Plugins. Depending on the number of installed plugins the process can take several minutes."));
-#else
-		q.set_title (_("Discover VST Plugins?"));
-    q.set_secondary_text (_("Third party plugins have not yet been indexed. VST plugins have to be scanned before they can be used. This can also be done manually from Preferences > Plugins. Depending on the number of installed plugins the process can take several minutes."));
+					_("VST/AU")
 #endif
+					_("VST")
+					));
 
-    if (q.run () == RESPONSE_YES) {
+		q.set_secondary_text (string_compose (_("Third party plugins have not yet been indexed. %1 plugins have to be scanned before they can be used. This can also be done manually from Window > Plugin Manager. Depending on the number of installed plugins the process can take several minutes."),
+#ifdef __APPLE__
+					_("AudioUnit and VST")
+#else
+					_("VST")
+#endif
+					));
+
+		if (q.run () == RESPONSE_YES) {
 			scan_now = true;
 		}
 	}