2 files changed, 22 insertions, 5 deletions

diff --git a/engines/sci/sound/drivers/cms.cpp b/engines/sci/sound/drivers/cms.cpp
index 0f79251ea7..091aab2414 100644
--- a/engines/sci/sound/drivers/cms.cpp
+++ b/engines/sci/sound/drivers/cms.cpp
@@ -740,7 +740,7 @@ int MidiDriver_CMS::open() {
 	Resource *res = _resMan->findResource(ResourceId(kResourceTypePatch, 101), false);
 	if (!res)
 		return -1;
-	
+
 	_patchData->allocateFromSpan(_version < SCI_VERSION_1_EARLY ? res->subspan(30) : *res);
 
 	_rate = _mixer->getOutputRate();
@@ -1294,7 +1294,7 @@ void MidiDriver_CMS::generateSamples(int16 *buffer, int len) {
 
 class MidiPlayer_CMS : public MidiPlayer {
 public:
-	MidiPlayer_CMS(SciVersion version) : MidiPlayer(version) {}
+	MidiPlayer_CMS(SciVersion version) : MidiPlayer(version), _filesMissing(false) {}
 
 	int open(ResourceManager *resMan);
 	void close();
@@ -1306,6 +1306,12 @@ public:
 	int getPolyphony() const { return 12; }
 
 	void playSwitch(bool play) { _driver->property(MidiDriver_CMS::MIDI_PROP_PLAYSWITCH, play ? 1 : 0); }
+
+	const char *reportMissingFiles() { return _filesMissing ? _requiredFiles : 0; }
+
+private:
+	bool _filesMissing;
+	static const char _requiredFiles[];
 };
 
 int MidiPlayer_CMS::open(ResourceManager *resMan) {
@@ -1314,10 +1320,11 @@ int MidiPlayer_CMS::open(ResourceManager *resMan) {
 
 	_driver = new MidiDriver_CMS(g_system->getMixer(), resMan, _version);
 	int driverRetVal = _driver->open();
-	if (driverRetVal != 0)
-		return driverRetVal;
 
-	return 0;
+	if (driverRetVal == -1)
+		_filesMissing = true;
+
+	return driverRetVal;
 }
 
 void MidiPlayer_CMS::close() {
@@ -1332,6 +1339,8 @@ void MidiPlayer_CMS::initTrack(SciSpan<const byte>& header) {
 		static_cast<MidiDriver_CMS*>(_driver)->initTrack(header);
 }
 
+const char MidiPlayer_CMS::_requiredFiles[] = "'PATCH.101'";
+
 MidiPlayer *MidiPlayer_CMS_create(SciVersion version) {
 	return new MidiPlayer_CMS(version);
 }
diff --git a/engines/sci/sound/drivers/mididriver.h b/engines/sci/sound/drivers/mididriver.h
index 73c2fd5737..de87d9dbdb 100644
--- a/engines/sci/sound/drivers/mididriver.h
+++ b/engines/sci/sound/drivers/mididriver.h
@@ -126,6 +126,14 @@ public:
 	// Some drivers also do other things in here.
 	virtual void initTrack(SciSpan<const byte> &) {}
 
+	// There are several sound drivers which weren' part of the
+	// original game setup and came in the form of aftermarket patches.
+	// This method allows each driver to report missing patch or other
+	// required files which will then be displayed in an error dialog box.
+	// The method returns only a single string (instead of a string list),
+	// because no more than two files will be required.
+	virtual const char *reportMissingFiles() { return 0; }
+
 protected:
 	SciVersion _version;
 };