diff --git a/source/common/filesystem/include/resourcefile.h b/source/common/filesystem/include/resourcefile.h
index 20b48e0b5..7940e90e1 100644
--- a/source/common/filesystem/include/resourcefile.h
+++ b/source/common/filesystem/include/resourcefile.h
@@ -190,7 +190,7 @@ public:
 		return (entry < NumLumps) ? Entries[entry].FileName : nullptr;
 	}
 
-	virtual FileData Read(int entry);
+	virtual FileData Read(uint32_t entry);
 
 	virtual FCompressedBuffer GetRawData(uint32_t entry);
 
diff --git a/source/common/filesystem/source/file_7z.cpp b/source/common/filesystem/source/file_7z.cpp
index 7efca8c9d..5e036b5eb 100644
--- a/source/common/filesystem/source/file_7z.cpp
+++ b/source/common/filesystem/source/file_7z.cpp
@@ -179,7 +179,7 @@ public:
 	F7ZFile(const char * filename, FileReader &filer, StringPool* sp);
 	bool Open(LumpFilterInfo* filter, FileSystemMessageFunc Printf);
 	virtual ~F7ZFile();
-	FileData Read(int entry) override;
+	FileData Read(uint32_t entry) override;
 	FileReader GetEntryReader(uint32_t entry, int, int) override;
 };
 
@@ -282,7 +282,7 @@ bool F7ZFile::Open(LumpFilterInfo *filter, FileSystemMessageFunc Printf)
 
 		FileData temp(nullptr, Entries[0].Length);
 
-		if (SZ_OK != Archive->Extract(Entries[0].Position, (char*)temp.writable()))
+		if (SZ_OK != Archive->Extract((UInt32)Entries[0].Position, (char*)temp.writable()))
 		{
 			Printf(FSMessageLevel::Error, "%s: unsupported 7z/LZMA file!\n", FileName);
 			return false;
@@ -314,15 +314,15 @@ F7ZFile::~F7ZFile()
 //
 //==========================================================================
 
-FileData F7ZFile::Read(int entry)
+FileData F7ZFile::Read(uint32_t entry)
 {
 	FileData buffer;
-	if ((entry >= 0 || entry < NumLumps) && Entries[entry].Length > 0)
+	if (entry < NumLumps && Entries[entry].Length > 0)
 	{
 		auto p = buffer.allocate(Entries[entry].Length);
 		// There is no realistic way to keep multiple references to a 7z file open without massive overhead so to make this thread-safe a mutex is the only option.
 		std::lock_guard<FCriticalSection> lock(critsec);
-		SRes code = Archive->Extract(Entries[entry].Position, (char*)p);
+		SRes code = Archive->Extract((UInt32)Entries[entry].Position, (char*)p);
 		if (code != SZ_OK) buffer.clear();
 	}
 	return buffer;
diff --git a/source/common/filesystem/source/file_zip.cpp b/source/common/filesystem/source/file_zip.cpp
index 3356fc1fa..9f10d00a7 100644
--- a/source/common/filesystem/source/file_zip.cpp
+++ b/source/common/filesystem/source/file_zip.cpp
@@ -332,7 +332,7 @@ FCompressedBuffer FZipFile::GetRawData(uint32_t entry)
 {
 	FCompressedBuffer cbuf;
 
-	if (entry >= NumLumps >> Entries[entry].Length == 0)
+	if (entry >= NumLumps || Entries[entry].Length == 0)
 	{
 		cbuf = { 0, 0, METHOD_STORED, 0, 0, nullptr };
 	}
diff --git a/source/common/filesystem/source/files_decompress.cpp b/source/common/filesystem/source/files_decompress.cpp
index 95c6c7f9b..95cce3c33 100644
--- a/source/common/filesystem/source/files_decompress.cpp
+++ b/source/common/filesystem/source/files_decompress.cpp
@@ -931,7 +931,7 @@ bool OpenDecompressor(FileReader& self, FileReader &parent, FileReader::Size len
 		{
 			FileData buffer(nullptr, length);
 			FZipExploder exploder;
-			if (exploder.Explode(buffer.writable(), length, *p, p->GetLength(), method - METHOD_IMPLODE_MIN) == -1)
+			if (exploder.Explode(buffer.writable(), (unsigned)length, *p, (unsigned)p->GetLength(), method - METHOD_IMPLODE_MIN) == -1)
 			{
 				if (exceptions)
 				{
@@ -947,7 +947,7 @@ bool OpenDecompressor(FileReader& self, FileReader &parent, FileReader::Size len
 		case METHOD_SHRINK:
 		{
 			FileData buffer(nullptr, length);
-			ShrinkLoop(buffer.writable(), length, *p, p->GetLength()); // this never fails.
+			ShrinkLoop(buffer.writable(), (unsigned)length, *p, (unsigned)p->GetLength()); // this never fails.
 			fr = new MemoryArrayReader(buffer);
 			flags &= ~(DCF_SEEKABLE | DCF_CACHED);
 			break;
diff --git a/source/common/filesystem/source/filesystem.cpp b/source/common/filesystem/source/filesystem.cpp
index 394735d85..b931920e9 100644
--- a/source/common/filesystem/source/filesystem.cpp
+++ b/source/common/filesystem/source/filesystem.cpp
@@ -101,10 +101,6 @@ struct FileSystem::LumpRecord
 
 	void SetFromLump(FResourceFile* file, int fileindex, int filenum, StringPool* sp, const char* name = nullptr)
 	{
-		if (fileindex == 649 && filenum == 0)
-		{
-			int a = 0;
-		}
 		resfile = file;
 		resindex = fileindex;
 		rfnum = filenum;
diff --git a/source/common/filesystem/source/resourcefile.cpp b/source/common/filesystem/source/resourcefile.cpp
index 3483bc64c..c2d23837d 100644
--- a/source/common/filesystem/source/resourcefile.cpp
+++ b/source/common/filesystem/source/resourcefile.cpp
@@ -709,7 +709,7 @@ FileReader FResourceFile::GetEntryReader(uint32_t entry, int readertype, int rea
 	return fr;
 }
 
-FileData FResourceFile::Read(int entry)
+FileData FResourceFile::Read(uint32_t entry)
 {
 	if (!(Entries[entry].Flags & RESFF_COMPRESSED) && Reader.isOpen())
 	{
diff --git a/source/common/models/model.cpp b/source/common/models/model.cpp
index ce61bfe54..a8ee8958f 100644
--- a/source/common/models/model.cpp
+++ b/source/common/models/model.cpp
@@ -163,7 +163,13 @@ unsigned FindModel(const char * path, const char * modelfile, bool silent)
 		if (!Models[i]->mFileName.CompareNoCase(fullname)) return i;
 	}
 
-	int len = fileSystem.FileLength(lump);
+	auto len = fileSystem.FileLength(lump);
+	if (len >= 0x80000000ll)
+	{
+		Printf(PRINT_HIGH, "LoadModel: File to large: '%s'\n", fullname.GetChars());
+		return -1;
+	}
+
 	auto lumpd = fileSystem.ReadFile(lump);
 	const char * buffer = lumpd.string();
 
@@ -208,7 +214,7 @@ unsigned FindModel(const char * path, const char * modelfile, bool silent)
 
 	if (model != nullptr)
 	{
-		if (!model->Load(path, lump, buffer, len))
+		if (!model->Load(path, lump, buffer, (int)len))
 		{
 			delete model;
 			return -1;
diff --git a/source/common/scripting/interface/vmnatives.cpp b/source/common/scripting/interface/vmnatives.cpp
index 317ae6bfd..7480f4c32 100644
--- a/source/common/scripting/interface/vmnatives.cpp
+++ b/source/common/scripting/interface/vmnatives.cpp
@@ -852,7 +852,7 @@ DEFINE_ACTION_FUNCTION(_Wads, GetLumpLength)
 {
 	PARAM_PROLOGUE;
 	PARAM_INT(lump);
-	ACTION_RETURN_INT(fileSystem.FileLength(lump));
+	ACTION_RETURN_INT((int)fileSystem.FileLength(lump));
 }
 
 //==========================================================================
diff --git a/source/common/textures/formats/flattexture.cpp b/source/common/textures/formats/flattexture.cpp
index 5f26df931..533b484b3 100644
--- a/source/common/textures/formats/flattexture.cpp
+++ b/source/common/textures/formats/flattexture.cpp
@@ -74,10 +74,9 @@ FImageSource *FlatImage_TryCreate(FileReader & file, int lumpnum)
 FFlatTexture::FFlatTexture (int lumpnum)
 : FImageSource(lumpnum)
 {
-	int area;
 	int bits;
 
-	area = fileSystem.FileLength (lumpnum);
+	auto area = fileSystem.FileLength (lumpnum);
 
 	switch (area)
 	{
diff --git a/source/common/textures/multipatchtexturebuilder.cpp b/source/common/textures/multipatchtexturebuilder.cpp
index f57b1f65b..25ea5bbef 100644
--- a/source/common/textures/multipatchtexturebuilder.cpp
+++ b/source/common/textures/multipatchtexturebuilder.cpp
@@ -285,7 +285,7 @@ void FMultipatchTextureBuilder::AddTexturesLump(const void *lumpdata, int lumpsi
 		}
 
 		// Check whether the amount of names reported is correct.
-		int lumplength = fileSystem.FileLength(patcheslump);
+		uint32_t lumplength = (uint32_t)fileSystem.FileLength(patcheslump);
 		if (numpatches > uint32_t((lumplength - 4) / 8))
 		{
 			Printf("PNAMES lump is shorter than required (%u entries reported but only %d bytes (%d entries) long\n",
@@ -398,12 +398,12 @@ void FMultipatchTextureBuilder::AddTexturesLumps(int lump1, int lump2, int patch
 	if (lump1 >= 0)
 	{
 		auto texdir = fileSystem.ReadFile(lump1);
-		AddTexturesLump(texdir.data(), fileSystem.FileLength(lump1), lump1, patcheslump, firstdup, true);
+		AddTexturesLump(texdir.data(), (int)fileSystem.FileLength(lump1), lump1, patcheslump, firstdup, true);
 	}
 	if (lump2 >= 0)
 	{
 		auto texdir = fileSystem.ReadFile(lump2);
-		AddTexturesLump(texdir.data(), fileSystem.FileLength(lump2), lump2, patcheslump, firstdup, false);
+		AddTexturesLump(texdir.data(), (int)fileSystem.FileLength(lump2), lump2, patcheslump, firstdup, false);
 	}
 }
 
diff --git a/source/common/utility/writezip.cpp b/source/common/utility/writezip.cpp
index 5c0b0e65b..a6f6f9a27 100644
--- a/source/common/utility/writezip.cpp
+++ b/source/common/utility/writezip.cpp
@@ -61,8 +61,8 @@ static std::pair<uint16_t, uint16_t> time_to_dos(struct tm *time)
 	}
 	else
 	{
-		val.first = (time->tm_year - 80) * 512 + (time->tm_mon + 1) * 32 + time->tm_mday;
-		val.second= time->tm_hour * 2048 + time->tm_min * 32 + time->tm_sec / 2;
+		val.first = time->tm_hour * 2048 + time->tm_min * 32 + time->tm_sec / 2;
+		val.second = (time->tm_year - 80) * 512 + (time->tm_mon + 1) * 32 + time->tm_mday;
 	}
 	return val;
 }
diff --git a/source/core/menu/usermap.cpp b/source/core/menu/usermap.cpp
index 8cf320e1e..72873fab3 100644
--- a/source/core/menu/usermap.cpp
+++ b/source/core/menu/usermap.cpp
@@ -71,7 +71,7 @@ void InsertMap(int lumpnum)
 	current->entries.Last().displayname = path.Last();
 	current->entries.Last().filename = fileSystem.GetFileFullName(lumpnum);
 	current->entries.Last().container = fileSystem.GetResourceFileName(fileSystem.GetFileContainer(lumpnum));
-	current->entries.Last().size = fileSystem.FileLength(lumpnum);
+	current->entries.Last().size = (int)fileSystem.FileLength(lumpnum);
 	auto mapinfo = FindMapByName(StripExtension(path.Last().GetChars()).GetChars());
 	if (mapinfo) current->entries.Last().info = mapinfo->name;
 }
diff --git a/source/core/raze_sound.cpp b/source/core/raze_sound.cpp
index 0ec4c4166..826c594d8 100644
--- a/source/core/raze_sound.cpp
+++ b/source/core/raze_sound.cpp
@@ -94,7 +94,7 @@ TArray<uint8_t> RazeSoundEngine::ReadSound(int lumpnum)
 	auto wlump = fileSystem.OpenFileReader(lumpnum);
 	TArray<uint8_t> buffer(wlump.GetLength(), true);
 	auto len = wlump.Read(buffer.data(), buffer.size());
-	buffer.Resize(len);
+	buffer.Resize((unsigned)len);
 	return buffer;
 }