diff --git a/engines/wintermute/base/base_file_manager.cpp b/engines/wintermute/base/base_file_manager.cpp
index 08358f90330..28e0b3af6ed 100644
--- a/engines/wintermute/base/base_file_manager.cpp
+++ b/engines/wintermute/base/base_file_manager.cpp
@@ -53,7 +53,8 @@ namespace Wintermute {
 //////////////////////////////////////////////////////////////////////
 
 //////////////////////////////////////////////////////////////////////
-BaseFileManager::BaseFileManager(Common::Language lang) {
+BaseFileManager::BaseFileManager(Common::Language lang, bool detectionMode) {
+	_detectionMode = detectionMode;
 	_language = lang;
 	_resources = nullptr;
 	initResources();
@@ -232,12 +233,14 @@ bool BaseFileManager::registerPackage(Common::FSNode file, const Common::String
 
 void BaseFileManager::initResources() {
 	_resources = Common::makeZipArchive("wintermute.zip");
-	if (!_resources) {
+	if (!_resources && !_detectionMode) { // Wintermute.zip is unavailable during detection
 		error("Couldn't load wintermute.zip");
 	}
-	assert(_resources->hasFile("syste_font.bmp"));
-	assert(_resources->hasFile("invalid.bmp"));
-	assert(_resources->hasFile("invalid_debug.bmp"));
+	if (_resources) {
+		assert(_resources->hasFile("syste_font.bmp"));
+		assert(_resources->hasFile("invalid.bmp"));
+		assert(_resources->hasFile("invalid_debug.bmp"));
+	}
 }
 
 //////////////////////////////////////////////////////////////////////////
@@ -277,7 +280,7 @@ bool BaseFileManager::hasFile(const Common::String &filename) {
 	if (_packages.hasFile(filename)) {
 		return true;    // We don't bother checking if the file can actually be opened, something bigger is wrong if that is the case.
 	}
-	if (_resources->hasFile(filename)) {
+	if (!_detectionMode && _resources->hasFile(filename)) {
 		return true;
 	}
 	return false;
@@ -337,7 +340,9 @@ Common::SeekableReadStream *BaseFileManager::openFileRaw(const Common::String &f
 		return ret;
 	}
 
-	ret = _resources->createReadStreamForMember(filename);
+	if (!_detectionMode) {
+		ret = _resources->createReadStreamForMember(filename);
+	}
 	if (ret) {
 		return ret;
 	}
diff --git a/engines/wintermute/base/base_file_manager.h b/engines/wintermute/base/base_file_manager.h
index 5fc626a314c..7ed3a6c7cbf 100644
--- a/engines/wintermute/base/base_file_manager.h
+++ b/engines/wintermute/base/base_file_manager.h
@@ -45,7 +45,7 @@ public:
 	Common::SeekableReadStream *openFile(const Common::String &filename, bool absPathWarning = true, bool keepTrackOf = true);
 	byte *readWholeFile(const Common::String &filename, uint32 *size = nullptr, bool mustExist = true);
 
-	BaseFileManager(Common::Language lang);
+	BaseFileManager(Common::Language lang, bool detectionMode = false);
 	virtual ~BaseFileManager();
 	// Used only for detection
 	bool registerPackages(const Common::FSList &fslist);
@@ -65,6 +65,7 @@ private:
 	Common::FSList _packagePaths;
 	bool findPackageSignature(Common::SeekableReadStream *f, uint32 *offset);
 	bool registerPackage(Common::FSNode package, const Common::String &filename = "", bool searchSignature = false);
+	bool _detectionMode;
 	Common::SearchSet _packages;
 	Common::Array<Common::SeekableReadStream *> _openFiles;
 	Common::Language _language;
diff --git a/engines/wintermute/wintermute.cpp b/engines/wintermute/wintermute.cpp
index f33452d11cb..ad26c425106 100644
--- a/engines/wintermute/wintermute.cpp
+++ b/engines/wintermute/wintermute.cpp
@@ -311,7 +311,7 @@ bool WintermuteEngine::getGameInfo(const Common::FSList &fslist, Common::String
 	caption = name = "(invalid)";
 	Common::SeekableReadStream *stream = nullptr;
 	// Quick-fix, instead of possibly breaking the persistence-system, let's just roll with it
-	BaseFileManager *fileMan = new BaseFileManager(Common::UNK_LANG);
+	BaseFileManager *fileMan = new BaseFileManager(Common::UNK_LANG, true);
 	fileMan->registerPackages(fslist);
 	stream = fileMan->openFile("startup.settings", false, false);