diff --git a/Core/GameEngine/Source/Common/INI/INIMapCache.cpp b/Core/GameEngine/Source/Common/INI/INIMapCache.cpp
index 5be4414bb70..40a8a8cd18a 100644
--- a/Core/GameEngine/Source/Common/INI/INIMapCache.cpp
+++ b/Core/GameEngine/Source/Common/INI/INIMapCache.cpp
@@ -31,6 +31,7 @@
 #include "PreRTS.h"	// This must go first in EVERY cpp file in the GameEngine
 
 #include "Lib/BaseType.h"
+#include "Lib/PathUtil.h"
 #include "Common/INI.h"
 #include "GameClient/MapUtil.h"
 #include "GameClient/GameText.h"
@@ -148,8 +149,12 @@ void INI::parseMapCacheDefinition( INI* ini )
 	if (md.m_nameLookupTag.isEmpty())
 	{
 		// maps without localized name tags
+		// TheSuperHackers @bugfix bobtista 14/08/2026 Read the leaf with either separator, because
+		// the map cache is written with the platform separator and a missing '\\' left this
+		// dereferencing nullptr + 1.
 		AsciiString tempdisplayname;
-		tempdisplayname = name.reverseFind('\\') + 1;
+		const char *separator = getLastPathSeparator(name.str());
+		tempdisplayname = separator ? separator + 1 : name.str();
 		md.m_displayName.translate(tempdisplayname);
 		if (md.m_numPlayers >= 2)
 		{
diff --git a/Core/GameEngine/Source/GameClient/MapUtil.cpp b/Core/GameEngine/Source/GameClient/MapUtil.cpp
index 1806c50741a..9a30c686b0d 100644
--- a/Core/GameEngine/Source/GameClient/MapUtil.cpp
+++ b/Core/GameEngine/Source/GameClient/MapUtil.cpp
@@ -60,12 +60,39 @@
 #include "GameLogic/FPUControl.h"
 #include "GameNetwork/GameInfo.h"
 #include "GameNetwork/NetworkDefs.h"
+#include "Lib/PathUtil.h"
 
 
 //-------------------------------------------------------------------------------
 // PRIVATE DATA ///////////////////////////////////////////////////////////////////////////////////
 static const char *mapExtension = ".map";
 
+static void appendPathSeparator( AsciiString &path )
+{
+	if (path.isNotEmpty())
+	{
+		const char last = path.getCharAt(path.getLength() - 1);
+		if (last != '/' && last != '\\')
+		{
+			path.concat(getNativePathSeparator());
+		}
+	}
+}
+
+static AsciiString getPathInDirectory( const AsciiString &directory, const char *filename )
+{
+	AsciiString path = directory;
+	appendPathSeparator(path);
+	path.concat(filename);
+	return path;
+}
+
+static const char *getPathLeaf( const AsciiString &path )
+{
+	const char *separator = getLastPathSeparator(path.str());
+	return separator ? separator + 1 : path.str();
+}
+
 static Int m_width = 0;						///< Height map width.
 static Int m_height = 0;					///< Height map height (y size of array).
 static Int m_borderSize = 0;			///< Non-playable border area.
@@ -331,12 +358,10 @@ AsciiString MapCache::getMapExtension() const
 
 void MapCache::writeCacheINI( const AsciiString &mapDir )
 {
-	AsciiString filepath = mapDir;
-	filepath.concat('\\');
+	AsciiString filepath = getPathInDirectory(mapDir, m_mapCacheName);
 
 	TheFileSystem->createDirectory(mapDir);
 
-	filepath.concat(m_mapCacheName);
 	FILE *fp = fopen(filepath.str(), "w");
 	DEBUG_ASSERTCRASH(fp != nullptr, ("Failed to create %s", filepath.str()));
 	if (fp == nullptr) {
@@ -499,8 +524,7 @@ Bool MapCache::clearUnseenMaps( const AsciiString &mapDir )
 void MapCache::loadMapsFromMapCacheINI( const AsciiString &mapDir )
 {
 	INI ini;
-	AsciiString fname;
-	fname.format("%s\\%s", mapDir.str(), m_mapCacheName);
+	AsciiString fname = getPathInDirectory(mapDir, m_mapCacheName);
 
 	if (TheFileSystem->doesFileExist(fname.str()))
 	{
@@ -514,8 +538,8 @@ Bool MapCache::loadMapsFromDisk( const AsciiString &mapDir, Bool isOfficial, Boo
 
 	FilenameList filepathList;
 	FilenameListIter filepathIt;
-	AsciiString toplevelPattern;
-	toplevelPattern.format("%s\\", mapDir.str());
+	AsciiString toplevelPattern = mapDir;
+	appendPathSeparator(toplevelPattern);
 	Bool mapListChanged = FALSE;
 	AsciiString filenamepattern;
 	filenamepattern.format("*.%s", getMapExtension().str());
@@ -530,14 +554,13 @@ Bool MapCache::loadMapsFromDisk( const AsciiString &mapDir, Bool isOfficial, Boo
 		AsciiString filepathLower = *filepathIt;
 		filepathLower.toLower();
 
-		const char *szFilenameLower = filepathLower.reverseFind('\\');
+		const char *szFilenameLower = getLastPathSeparator(filepathLower.str());
 		if (!szFilenameLower)
 		{
-			DEBUG_CRASH(("Couldn't find \\ in map name!"));
+			DEBUG_CRASH(("Couldn't find path separator in map name!"));
 			continue;
 		}
 
-		AsciiString endingStr;
 		AsciiString filenameLower = szFilenameLower+1;
 		filenameLower.truncateBy(strlen(mapExtension));
 
@@ -547,7 +570,8 @@ Bool MapCache::loadMapsFromDisk( const AsciiString &mapDir, Bool isOfficial, Boo
 			continue;
 		}
 
-		endingStr.format("%s\\%s%s", filenameLower.str(), filenameLower.str(), mapExtension);
+		AsciiString endingStr;
+		endingStr.format("%s%c%s%s", filenameLower.str(), *szFilenameLower, filenameLower.str(), mapExtension);
 
 		if (!filepathLower.endsWithNoCase(endingStr.str()))
 		{
@@ -592,7 +616,7 @@ Bool MapCache::addMap(
 			{
 				// unofficial maps or maps without names
 				AsciiString tempdisplayname;
-				tempdisplayname = fname.reverseFind('\\') + 1;
+				tempdisplayname = getPathLeaf(fname);
 				(*this)[lowerFname].m_displayName.translate(tempdisplayname);
 				if (md.m_numPlayers >= 2)
 				{
@@ -654,7 +678,7 @@ Bool MapCache::addMap(
 	{
 		DEBUG_LOG(("Missing TheKey_mapName!"));
 		AsciiString tempdisplayname;
-		tempdisplayname = fname.reverseFind('\\') + 1;
+		tempdisplayname = getPathLeaf(fname);
 		md.m_displayName.translate(tempdisplayname);
 		if (md.m_numPlayers >= 2)
 		{
diff --git a/Core/Libraries/Include/Lib/PathUtil.h b/Core/Libraries/Include/Lib/PathUtil.h
index cf1ce769d91..eddade82485 100644
--- a/Core/Libraries/Include/Lib/PathUtil.h
+++ b/Core/Libraries/Include/Lib/PathUtil.h
@@ -23,6 +23,29 @@
 #include "BaseType.h"
 #include <string.h>
 
+inline char getNativePathSeparator()
+{
+#ifdef _WIN32
+	return '\\';
+#else
+	return '/';
+#endif
+}
+
+inline const char* getLastPathSeparator(const char* path)
+{
+	const char* forward = strrchr(path, '/');
+	const char* backward = strrchr(path, '\\');
+	return !forward ? backward : (!backward || forward > backward ? forward : backward);
+}
+
+inline const wchar_t* getLastPathSeparator(const wchar_t* path)
+{
+	const wchar_t* forward = wcsrchr(path, L'/');
+	const wchar_t* backward = wcsrchr(path, L'\\');
+	return !forward ? backward : (!backward || forward > backward ? forward : backward);
+}
+
 inline const char* getExtension(const char* path)
 {
 	const char* lastDot = strrchr(path, '.');
@@ -32,7 +55,7 @@ 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)
@@ -52,7 +75,7 @@ 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)