diff --git a/Core/GameEngine/Include/Common/FileSystem.h b/Core/GameEngine/Include/Common/FileSystem.h
index 2aaa30a61f1..a91c86bb2bd 100644
--- a/Core/GameEngine/Include/Common/FileSystem.h
+++ b/Core/GameEngine/Include/Common/FileSystem.h
@@ -163,6 +163,8 @@ class FileSystem : public SubsystemInterface
 	static bool removeExtension(AsciiString& path);
 	static bool removeExtension(UnicodeString& path);
 
+	static void appendPathSeparator(AsciiString& path);	///< appends the platform separator, unless the path is empty or already ends with either separator.
+
 protected:
 #if ENABLE_FILESYSTEM_EXISTENCE_CACHE
 	struct FileExistData
diff --git a/Core/GameEngine/Source/Common/System/FileSystem.cpp b/Core/GameEngine/Source/Common/System/FileSystem.cpp
index b8e4c4695b6..654e7575500 100644
--- a/Core/GameEngine/Source/Common/System/FileSystem.cpp
+++ b/Core/GameEngine/Source/Common/System/FileSystem.cpp
@@ -395,6 +395,17 @@ bool FileSystem::removeExtension(AsciiString& path)
 	return false;
 }
 
+//============================================================================
+// FileSystem::appendPathSeparator
+//============================================================================
+void FileSystem::appendPathSeparator(AsciiString& path)
+{
+	if (path.isNotEmpty() && !isPathSeparator(path.getCharAt(path.getLength() - 1)))
+	{
+		path.concat(getNativePathSeparator());
+	}
+}
+
 //============================================================================
 // FileSystem::removeExtension - Unicode handling variant
 //============================================================================
diff --git a/Core/GameEngine/Source/GameNetwork/FileTransfer.cpp b/Core/GameEngine/Source/GameNetwork/FileTransfer.cpp
index 5d9cc7dfe64..3f10ecb5e5b 100644
--- a/Core/GameEngine/Source/GameNetwork/FileTransfer.cpp
+++ b/Core/GameEngine/Source/GameNetwork/FileTransfer.cpp
@@ -30,10 +30,12 @@
 
 #include "PreRTS.h"	// This must go first in EVERY cpp file in the GameEngine
 
+#include "Common/FileSystem.h"
 #include "GameClient/LoadScreen.h"
 #include "GameClient/Shell.h"
 #include "GameNetwork/FileTransfer.h"
 #include "GameNetwork/networkutil.h"
+#include "Lib/PathUtil.h"
 
 //-------------------------------------------------------------------------------------
 //-------------------------------------------------------------------------------------
@@ -137,7 +139,7 @@ static Bool doFileTransfer( AsciiString filename, MapTransferLoadScreen *ls, Int
 
 AsciiString GetBasePathFromPath( AsciiString path )
 {
-	const char *s = path.reverseFind('\\');
+	const char *s = getLastPathSeparator(path.str());
 	if (s)
 	{
 		Int len = s - path.str();
@@ -153,10 +155,7 @@ AsciiString GetBasePathFromPath( AsciiString path )
 
 AsciiString GetFileFromPath( AsciiString path )
 {
-	const char *s = path.reverseFind('\\');
-	if (s)
-		return s+1;
-	return path;
+	return getFileName(path.str());
 }
 
 AsciiString GetExtensionFromFile( AsciiString fname )
@@ -183,59 +182,45 @@ AsciiString GetBaseFileFromFile( AsciiString fname )
 	return AsciiString::TheEmptyString;
 }
 
-AsciiString GetPreviewFromMap( AsciiString path )
+static AsciiString GetFileInMapDirectory( const AsciiString &mapPath, const AsciiString &filename )
 {
-	AsciiString fname = GetBaseFileFromFile(GetFileFromPath(path));
-	AsciiString base = GetBasePathFromPath(path);
+	const char *file = getFileName(mapPath.str());
+	AsciiString path;
+	path.set(mapPath.str(), file - mapPath.str());
+	path.concat(filename);
+	return path;
+}
 
-	AsciiString out;
-	out.format("%s\\%s.tga", base.str(), fname.str());
-	return out;
+AsciiString GetPreviewFromMap( AsciiString path )
+{
+	FileSystem::removeExtension(path);
+	path.concat(".tga");
+	return path;
 }
 
 AsciiString GetINIFromMap( AsciiString path )
 {
-	AsciiString base = GetBasePathFromPath(path);
-
-	AsciiString out;
-	out.format("%s\\map.ini", base.str());
-	return out;
+	return GetFileInMapDirectory(path, "map.ini");
 }
 
 AsciiString GetStrFileFromMap( AsciiString path )
 {
-	AsciiString base = GetBasePathFromPath(path);
-
-	AsciiString out;
-	out.format("%s\\map.str", base.str());
-	return out;
+	return GetFileInMapDirectory(path, "map.str");
 }
 
 AsciiString GetSoloINIFromMap( AsciiString path )
 {
-	AsciiString base = GetBasePathFromPath(path);
-
-	AsciiString out;
-	out.format("%s\\solo.ini", base.str());
-	return out;
+	return GetFileInMapDirectory(path, "solo.ini");
 }
 
 AsciiString GetAssetUsageFromMap( AsciiString path )
 {
-	AsciiString base = GetBasePathFromPath(path);
-
-	AsciiString out;
-	out.format("%s\\assetusage.txt", base.str());
-	return out;
+	return GetFileInMapDirectory(path, "assetusage.txt");
 }
 
 AsciiString GetReadmeFromMap( AsciiString path )
 {
-	AsciiString base = GetBasePathFromPath(path);
-
-	AsciiString out;
-	out.format("%s\\readme.txt", base.str());
-	return out;
+	return GetFileInMapDirectory(path, "readme.txt");
 }
 
 //-------------------------------------------------------------------------------------
diff --git a/Core/Libraries/Include/Lib/PathUtil.h b/Core/Libraries/Include/Lib/PathUtil.h
index 683f6fee130..ad6c00d6283 100644
--- a/Core/Libraries/Include/Lib/PathUtil.h
+++ b/Core/Libraries/Include/Lib/PathUtil.h
@@ -23,7 +23,8 @@
 #include "BaseType.h"
 #include <string.h>
 
-inline bool isPathSeparator(char ch)
+// Returns true for a separator the host platform uses to open files.
+inline bool isNativePathSeparator(char ch)
 {
 #ifdef _WIN32
 	return ch == '\\' || ch == '/';
@@ -32,6 +33,12 @@ inline bool isPathSeparator(char ch)
 #endif
 }
 
+// Returns true for either separator. Game data paths carry '\\' on every platform.
+inline bool isPathSeparator(char ch)
+{
+	return ch == '/' || ch == '\\';
+}
+
 inline bool isAbsolutePath(const char* path)
 {
 	if (path == nullptr)
@@ -39,14 +46,14 @@ inline bool isAbsolutePath(const char* path)
 		return false;
 	}
 
-	if (isPathSeparator(path[0]))
+	if (isNativePathSeparator(path[0]))
 	{
 		return true;
 	}
 
 #ifdef _WIN32
 	const bool hasDriveLetter = (path[0] >= 'A' && path[0] <= 'Z') || (path[0] >= 'a' && path[0] <= 'z');
-	if (hasDriveLetter && path[1] == ':' && isPathSeparator(path[2]))
+	if (hasDriveLetter && path[1] == ':' && isNativePathSeparator(path[2]))
 	{
 		return true;
 	}
@@ -55,6 +62,32 @@ inline bool isAbsolutePath(const char* path)
 	return false;
 }
 
+inline char getNativePathSeparator()
+{
+#ifdef _WIN32
+	return '\\';
+#else
+	return '/';
+#endif
+}
+
+inline const char* getLastPathSeparator(const char* path)
+{
+	return path ? maxPtr(strrchr(path, '/'), strrchr(path, '\\')) : nullptr;
+}
+
+inline const wchar_t* getLastPathSeparator(const wchar_t* path)
+{
+	return path ? maxPtr(wcsrchr(path, L'/'), wcsrchr(path, L'\\')) : nullptr;
+}
+
+// Returns the whole path when it contains no separator
+inline const char* getFileName(const char* path)
+{
+	const char* lastSeparator = getLastPathSeparator(path);
+	return lastSeparator ? lastSeparator + 1 : path;
+}
+
 inline const char* getExtension(const char* path)
 {
 	const char* lastDot = strrchr(path, '.');
@@ -64,7 +97,7 @@ inline const char* getExtension(const char* path)
 		return nullptr;
 	}
 
-	const char* lastSeparator = maxPtr(strrchr(path, '/'), strrchr(path, '\\'));
+	const char* lastSeparator = getLastPathSeparator(path);
 
 	// Check if the dot is contained in the filename
 	if (lastSeparator && lastDot < lastSeparator)
@@ -84,7 +117,7 @@ inline const wchar_t* getExtension(const wchar_t* path)
 		return nullptr;
 	}
 
-	const wchar_t* lastSeparator = maxPtr(wcsrchr(path, L'/'), wcsrchr(path, L'\\'));
+	const wchar_t* lastSeparator = getLastPathSeparator(path);
 
 	// Check if the dot is contained in the filename
 	if (lastSeparator && lastDot < lastSeparator)