diff --git a/source/games/blood/src/blood.cpp b/source/games/blood/src/blood.cpp
index aa00efbe4..a90745598 100644
--- a/source/games/blood/src/blood.cpp
+++ b/source/games/blood/src/blood.cpp
@@ -552,9 +552,9 @@ void GameInterface::loadPalette(void)
 
 	for (int i = 0; i < 5; i++)
 	{
-		auto pal = fileSystem.LoadFile(PAL[i]);
-		if (pal.size() < 768) I_FatalError("%s: file too small", PAL[i]);
-		paletteSetColorTable(i, pal.data(), false, false);
+		auto pal = fileSystem.ReadFileFullName(PAL[i]);
+		if (pal.GetSize() < 768) I_FatalError("%s: file too small", PAL[i]);
+		paletteSetColorTable(i, (const uint8_t*)pal.GetMem(), false, false);
 	}
 
 	numshades = 64;
@@ -566,13 +566,13 @@ void GameInterface::loadPalette(void)
 			if (i < 15) I_FatalError("%s: file not found", PLU[i]);
 			else continue;
 		}
-		auto data = fileSystem.GetFileData(lump);
-		if (data.size() != 64 * 256)
+		auto data = fileSystem.ReadFile(lump);
+		if (data.GetSize() != 64 * 256)
 		{
 			if (i < 15) I_FatalError("%s: Incorrect PLU size", PLU[i]);
 			else continue;
 		}
-		lookups.setTable(i, data.data());
+		lookups.setTable(i, (const uint8_t*)data.GetMem());
 	}
 
 	lookups.setFadeColor(1, 255, 255, 255);
diff --git a/source/games/duke/src/gamedef.cpp b/source/games/duke/src/gamedef.cpp
index 3d9e1b924..5035c7b2c 100644
--- a/source/games/duke/src/gamedef.cpp
+++ b/source/games/duke/src/gamedef.cpp
@@ -118,7 +118,7 @@ struct TempMusic
 
 class ConCompiler
 {
-	char* textptr = nullptr;
+	const char* textptr = nullptr;
 	int line_number = 0;
 	int errorcount = 0, warningcount = 0;	// was named 'error' and 'warning' which is too generic for public variables and may clash with other code.
 	int currentsourcefile = -1;
@@ -782,7 +782,7 @@ void ConCompiler::checkforkeyword()
 int ConCompiler::CountCaseStatements()
 {
 	int lCount;
-	char* temptextptr;
+	const char* temptextptr;
 	int savescript;
 	int savecase;
 	int temp_line_number;
@@ -1079,7 +1079,7 @@ int ConCompiler::parsecommand()
 			return 0;
 		}
 
-		auto data = fileSystem.GetFileData(fni, 1);
+		auto data = fileSystem.ReadFile(fni);
 
 		temp_current_file = currentsourcefile;
 		currentsourcefile = fni;
@@ -1089,7 +1089,7 @@ int ConCompiler::parsecommand()
 		temp_ifelse_check = checking_ifelse;
 		checking_ifelse = 0;
 		auto origtptr = textptr;
-		textptr = (char*)data.data();
+		textptr = data.GetString();
 
 		do
 			done = parsecommand();
@@ -3106,8 +3106,8 @@ void ConCompiler::compilecon(const char *filenam)
 		I_FatalError("%s: Missing con file(s).", filenam);
 	}
 	Printf("Compiling: '%s'.\n", filenam);
-	auto data = fileSystem.GetFileData(currentsourcefile, 1);
-	textptr = (char*)data.data();
+	auto data = fileSystem.ReadFile(currentsourcefile);
+	textptr = data.GetString();
 
 	line_number = 1;
 	errorcount = warningcount = 0;
diff --git a/source/games/exhumed/src/sound.cpp b/source/games/exhumed/src/sound.cpp
index 7adb28d5a..b9c1a5979 100644
--- a/source/games/exhumed/src/sound.cpp
+++ b/source/games/exhumed/src/sound.cpp
@@ -175,9 +175,9 @@ int LoadSound(const char* name)
     auto lump = S_LookupSound(filename);
     if (lump > 0)
     {
-        auto check = fileSystem.GetFileData(lump);
+        auto check = fileSystem.ReadFile(lump);
 		bool loops = false;
-        if (check.size() > 26 && check[26] == 6 && !memcmp("Creative Voice File", check.data(), 19))
+        if (check.GetSize() > 26 && check.GetString()[26] == 6 && !memcmp("Creative Voice File", check.GetString(), 19))
         {
             // This game uses the actual loop point information in the sound data as its only means to check if a sound is looped.
             loops = true;
diff --git a/source/games/sw/src/colormap.cpp b/source/games/sw/src/colormap.cpp
index 81e522687..bbf8312b4 100644
--- a/source/games/sw/src/colormap.cpp
+++ b/source/games/sw/src/colormap.cpp
@@ -231,15 +231,20 @@ void GameInterface::loadPalette(void)
     unsigned int i;
     int play;
     uint8_t tempbuf[256];
+    uint8_t pal[768];
 
     paletteLoadFromDisk();
-    auto pal = fileSystem.LoadFile("3drealms.pal", 0);
-    if (pal.size() >= 768)
+    auto palr = fileSystem.OpenFileReader("3drealms.pal");
+    if (palr.isOpen())
     {
-        for (auto& c : pal)
-            c <<= 2;
+        auto siz = palr.Read(pal, 768);
+        if (siz == 768)
+        {
+            for (auto& c : pal)
+                c <<= 2;
 
-        paletteSetColorTable(DREALMSPAL, pal.data(), true, true);
+            paletteSetColorTable(DREALMSPAL, pal, true, true);
+        }
     }