4 files changed, 17 insertions, 3 deletions
diff --git a/engines/dm/detection.cpp b/engines/dm/detection.cpp
index 8361ec300d..e8ec79a176 100644
--- a/engines/dm/detection.cpp
+++ b/engines/dm/detection.cpp
@@ -77,7 +77,7 @@ static const DMADGameDescription gameDescriptions[] = {
 				{"DemoDun.dat", 0, "78848e1a2d3d5a11e5954deb8c7b772b", 1209},
 				AD_LISTEND
 			},
-			Common::EN_ANY, Common::kPlatformAmiga, ADGF_NO_FLAGS, GUIO1(GUIO_NONE),
+			Common::EN_ANY, Common::kPlatformAmiga, ADGF_DEMO, GUIO1(GUIO_NONE),
 		},
 		kDMSaveTargetDM21, kDMSaveFormatAmigaPC98FmTowns, kDMSavePlatformAtariSt,
 		{ kDMSaveTargetDM21, kDMSaveTargetEndOfList},
diff --git a/engines/dm/dm.cpp b/engines/dm/dm.cpp
index cfed9eb894..25d741f376 100644
--- a/engines/dm/dm.cpp
+++ b/engines/dm/dm.cpp
@@ -68,6 +68,11 @@
 #include "dm/sounds.h"
 
 namespace DM {
+
+bool DMEngine::isDemo() const {
+	return (bool)(_gameVersion->_desc.flags & ADGF_DEMO);
+}
+
 Direction DMEngine::turnDirRight(int16 dir) {
 	Direction result = (Direction)((dir + 1) & 3);
 	return result;
diff --git a/engines/dm/dm.h b/engines/dm/dm.h
index 6549db13b5..9056a744fb 100644
--- a/engines/dm/dm.h
+++ b/engines/dm/dm.h
@@ -211,7 +211,7 @@ public:
 
 // Note: F0026_MAIN_GetBoundedValue<T> has been replaced by CLIP<T>
 
-#define CALL_MEMBER_FN(object,ptrToMember)  ((object).*(ptrToMember))
+#define CALL_MEMBER_FN(object, ptrToMember)  ((object).*(ptrToMember))
 
 struct SaveGameHeader {
 	byte _version;
@@ -243,6 +243,8 @@ public:
 	virtual Common::Error loadGameState(int slot);
 	virtual bool canLoadGameStateCurrently();
 
+	bool isDemo() const;
+
 	GUI::Debugger *getDebugger() { return _console; }
 
 	void delay(uint16 verticalBlank); // @ F0022_MAIN_Delay
diff --git a/engines/dm/dungeonman.cpp b/engines/dm/dungeonman.cpp
index 5746ee03c2..417f3e31e7 100644
--- a/engines/dm/dungeonman.cpp
+++ b/engines/dm/dungeonman.cpp
@@ -477,7 +477,14 @@ DungeonMan::~DungeonMan() {
 
 void DungeonMan::decompressDungeonFile() {
 	Common::File f;
-	f.open("Dungeon.dat");
+	if (_vm->isDemo())
+		f.open("DemoDun.dat");
+	else
+		f.open("Dungeon.dat");
+
+	if (!f.isOpen())
+		error("Unable to open Dungeon.dat file");
+
 	if (f.readUint16BE() == 0x8104) { // if dungeon is compressed
 		_rawDunFileDataSize = f.readUint32BE();
 		delete[] _rawDunFileData;