diff --git a/Core/NES/Loaders/BaseLoader.h b/Core/NES/Loaders/BaseLoader.h
index a6ae101d..52d57ff0 100644
--- a/Core/NES/Loaders/BaseLoader.h
+++ b/Core/NES/Loaders/BaseLoader.h
@@ -5,18 +5,13 @@
 class BaseLoader
 {
 protected:
-	bool _checkOnly;
-
 	void Log(string message)
 	{
-		if(!_checkOnly) {
-			MessageManager::Log(message);
-		}
+		MessageManager::Log(message);
 	}
 
 public:
-	BaseLoader(bool checkOnly = false)
+	BaseLoader()
 	{
-		_checkOnly = checkOnly;
 	}
 };
\ No newline at end of file
diff --git a/Core/NES/Loaders/FdsLoader.cpp b/Core/NES/Loaders/FdsLoader.cpp
index 0086575a..787167a2 100644
--- a/Core/NES/Loaders/FdsLoader.cpp
+++ b/Core/NES/Loaders/FdsLoader.cpp
@@ -10,37 +10,78 @@
 #include "Utilities/FolderUtilities.h"
 #include "Utilities/CRC32.h"
 #include "Utilities/sha1.h"
+#include "Utilities/HexUtilities.h"
+#include "Utilities/StringUtilities.h"
 
-void FdsLoader::AddGaps(vector<uint8_t>& diskSide, uint8_t * readBuffer)
+FdsLoader::FdsLoader(bool useQdFormat) : BaseLoader()
+{
+	_useQdFormat = useQdFormat;
+}
+
+int FdsLoader::GetSideCapacity()
+{
+	return _useQdFormat ? QdDiskSideCapacity : FdsDiskSideCapacity;
+}
+
+void FdsLoader::AddGaps(vector<uint8_t>& diskSide, uint8_t* readBuffer, uint32_t bufferSize)
 {
 	//Start image with 28300 bits of gap
 	diskSide.insert(diskSide.end(), 28300 / 8, 0);
 
-	for(size_t j = 0; j < FdsDiskSideCapacity;) {
-		uint8_t blockType = readBuffer[j];
+	auto read = [&](int i) -> uint8_t {
+		if(i >= 0 && i < bufferSize) {
+			return readBuffer[i];
+		}
+		return 0;
+	};
+
+	for(int j = 0; j < GetSideCapacity();) {
+		uint8_t blockType = read(j);
 		uint32_t blockLength = 1;
 		switch(blockType) {
 			case 1: blockLength = 56; break; //Disk header
 			case 2: blockLength = 2; break; //File count
-			case 3: blockLength = 16; break; //File header
-			case 4: blockLength = 1 + readBuffer[j - 3] + readBuffer[j - 2] * 0x100; break;
+			
+			case 3:
+				//File header
+				//Log("ID: $" + HexUtilities::ToHex(read(j + 1)) + " - $" + HexUtilities::ToHex(read(j + 2)) + " - " + StringUtilities::GetString(readBuffer + j + 3, 8));
+				//Log("Size: $" + HexUtilities::ToHex(read(j + 0x0D) | (read(j+0x0E) << 8)));
+				//Log("Load address: $" + HexUtilities::ToHex(read(j + 0x0B) | (read(j + 0x0C) << 8)));
+				blockLength = 16;
+				break;
+
+			case 4:
+				if(_useQdFormat) {
+					blockLength = 1 + (read(j - 5) | (read(j - 4) << 8));
+				} else {
+					blockLength = 1 + (read(j - 3) | (read(j - 2) << 8));
+				}
+				break;
+
 			default: return; //End parsing when we encounter an invalid block type (This is what Nestopia apppears to do)
 		}
 
-		if(blockType == 0) {
-			diskSide.push_back(blockType);
-		} else {
-			diskSide.push_back(0x80);
-			diskSide.insert(diskSide.end(), &readBuffer[j], &readBuffer[j] + blockLength);
+		if(_useQdFormat) {
+			//Use CRC values from QD file
+			blockLength += 2;
+		}
 
+		if(j + blockLength >= bufferSize) {
+			return;
+		}
+
+		diskSide.push_back(0x80);
+		diskSide.insert(diskSide.end(), &readBuffer[j], &readBuffer[j] + blockLength);
+
+		if(!_useQdFormat) {
 			//Fake CRC value
 			diskSide.push_back(0x4D);
 			diskSide.push_back(0x62);
-
-			//Insert 976 bits of gap after a block
-			diskSide.insert(diskSide.end(), 976 / 8, 0);
 		}
 
+		//Insert 976 bits of gap after a block
+		diskSide.insert(diskSide.end(), 976 / 8, 0);
+
 		j += blockLength;
 	}
 }
@@ -48,7 +89,7 @@ void FdsLoader::AddGaps(vector<uint8_t>& diskSide, uint8_t * readBuffer)
 vector<uint8_t> FdsLoader::RebuildFdsFile(vector<vector<uint8_t>> diskData, bool needHeader)
 {
 	vector<uint8_t> output;
-	output.reserve(diskData.size() * FdsDiskSideCapacity + 16);
+	output.reserve(diskData.size() * GetSideCapacity() + 16);
 
 	if(needHeader) {
 		uint8_t header[16] = { 'F', 'D', 'S', '\x1a', (uint8_t)diskData.size(), '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0' };
@@ -58,7 +99,7 @@ vector<uint8_t> FdsLoader::RebuildFdsFile(vector<vector<uint8_t>> diskData, bool
 	for(vector<uint8_t> &diskSide : diskData) {
 		bool inGap = true;
 		size_t i = 0, len = diskSide.size();
-		size_t gapNeeded = FdsDiskSideCapacity;
+		size_t gapNeeded = GetSideCapacity();
 		uint32_t fileSize = 0;
 		while(i < len) {
 			if(inGap) {
@@ -74,10 +115,18 @@ vector<uint8_t> FdsLoader::RebuildFdsFile(vector<vector<uint8_t>> diskData, bool
 					case 3: blockLength = 16; fileSize = diskSide[i + 13] + diskSide[i + 14] * 0x100;  break; //File header
 					case 4: blockLength = 1 + fileSize; break;
 				}
+
+				if(_useQdFormat) {
+					blockLength += 2;
+				}
+
 				output.insert(output.end(), &diskSide[i], &diskSide[i] + blockLength);
 				gapNeeded -= blockLength;
 				i += blockLength;
-				i += 2; //Skip CRC after block
+
+				if(!_useQdFormat) {
+					i += 2; //Skip CRC after block
+				}
 
 				inGap = true;
 			}
@@ -97,7 +146,7 @@ void FdsLoader::LoadDiskData(vector<uint8_t>& romFile, vector<vector<uint8_t>>&
 		numberOfSides = romFile[4];
 		fileOffset = 16;
 	} else {
-		numberOfSides = (uint8_t)(romFile.size() / 65500);
+		numberOfSides = (uint8_t)(romFile.size() / GetSideCapacity());
 	}
 
 	for(uint32_t i = 0; i < numberOfSides; i++) {
@@ -106,12 +155,12 @@ void FdsLoader::LoadDiskData(vector<uint8_t>& romFile, vector<vector<uint8_t>>&
 
 		diskHeaders.push_back(vector<uint8_t>(romFile.data() + fileOffset + 1, romFile.data() + fileOffset + 57));
 
-		AddGaps(fdsDiskImage, &romFile[fileOffset]);
-		fileOffset += FdsDiskSideCapacity;
+		AddGaps(fdsDiskImage, &romFile[fileOffset], romFile.size() - fileOffset);
+		fileOffset += GetSideCapacity();
 
-		//Ensure the image is 65500 bytes
-		if(fdsDiskImage.size() < FdsDiskSideCapacity) {
-			fdsDiskImage.resize(FdsDiskSideCapacity);
+		//Ensure the image is at least the expected size of a disk
+		if(fdsDiskImage.size() < GetSideCapacity()) {
+			fdsDiskImage.resize(GetSideCapacity());
 		}
 	}
 }
diff --git a/Core/NES/Loaders/FdsLoader.h b/Core/NES/Loaders/FdsLoader.h
index d0dae5ce..aec4914c 100644
--- a/Core/NES/Loaders/FdsLoader.h
+++ b/Core/NES/Loaders/FdsLoader.h
@@ -8,12 +8,17 @@ class FdsLoader : public BaseLoader
 {
 private:
 	static constexpr size_t FdsDiskSideCapacity = 65500;
+	static constexpr size_t QdDiskSideCapacity = 65536;
+
+	bool _useQdFormat = false;
 
 private:
-	void AddGaps(vector<uint8_t>& diskSide, uint8_t* readBuffer);
+	void AddGaps(vector<uint8_t>& diskSide, uint8_t* readBuffer, uint32_t bufferSize);
+
+	int GetSideCapacity();
 
 public:
-	using BaseLoader::BaseLoader;
+	FdsLoader(bool useQdFormat = false);
 
 	vector<uint8_t> RebuildFdsFile(vector<vector<uint8_t>> diskData, bool needHeader);
 	void LoadDiskData(vector<uint8_t>& romFile, vector<vector<uint8_t>> &diskData, vector<vector<uint8_t>> &diskHeaders);
diff --git a/Core/NES/Loaders/UnifLoader.cpp b/Core/NES/Loaders/UnifLoader.cpp
index 0276f2b8..61dc74fd 100644
--- a/Core/NES/Loaders/UnifLoader.cpp
+++ b/Core/NES/Loaders/UnifLoader.cpp
@@ -191,14 +191,10 @@ void UnifLoader::LoadRom(RomData& romData, vector<uint8_t>& romFile, bool databa
 		Log("[UNIF] Mirroring: " + mirroringType);
 		Log("[UNIF] Battery: " + string(romData.Info.HasBattery ? "Yes" : "No"));
 
-		if(!_checkOnly) {
-			GameDatabase::SetGameInfo(romData.Info.Hash.PrgChrCrc32, romData, databaseEnabled, false);
-		}
+		GameDatabase::SetGameInfo(romData.Info.Hash.PrgChrCrc32, romData, databaseEnabled, false);
 
 		if(romData.Info.MapperID == UnifBoards::UnknownBoard) {
-			if(!_checkOnly) {
-				MessageManager::DisplayMessage("Error", "UnsupportedMapper", "UNIF: " + _mapperName);
-			}
+			MessageManager::DisplayMessage("Error", "UnsupportedMapper", "UNIF: " + _mapperName);
 			romData.Error = true;
 		}
 	}
diff --git a/Core/NES/Loaders/iNesLoader.cpp b/Core/NES/Loaders/iNesLoader.cpp
index f5f537aa..448ed152 100644
--- a/Core/NES/Loaders/iNesLoader.cpp
+++ b/Core/NES/Loaders/iNesLoader.cpp
@@ -142,7 +142,7 @@ void iNesLoader::LoadRom(RomData& romData, vector<uint8_t>& romFile, NesHeader *
 		Log("[iNes] EPSM: Yes");
 	}
 
-	if(!_checkOnly && !romData.Info.IsNes20Header) {
+	if(!romData.Info.IsNes20Header) {
 		GameDatabase::SetGameInfo(romData.Info.Hash.PrgChrCrc32, romData, databaseEnabled, preloadedHeader != nullptr);
 	}
 
diff --git a/Core/NES/Mappers/FDS/Fds.cpp b/Core/NES/Mappers/FDS/Fds.cpp
index 2c6f4f0e..58670c98 100644
--- a/Core/NES/Mappers/FDS/Fds.cpp
+++ b/Core/NES/Mappers/FDS/Fds.cpp
@@ -15,6 +15,7 @@
 #include "Shared/FirmwareHelper.h"
 #include "Utilities/Patches/IpsPatcher.h"
 #include "Utilities/Serializer.h"
+#include "Utilities/StringUtilities.h"
 
 void Fds::InitMapper()
 {
@@ -48,8 +49,10 @@ void Fds::InitMapper(RomData &romData)
 	_fdsDiskSides = romData.FdsDiskData;
 	_fdsDiskHeaders = romData.FdsDiskHeaders;
 	_fdsRawData = romData.RawData;
+	string filename = StringUtilities::ToLower(romData.Info.Filename);
+	_useQdFormat = StringUtilities::EndsWith(filename, ".qd");
 
-	FdsLoader loader;
+	FdsLoader loader(_useQdFormat);
 	loader.LoadDiskData(_fdsRawData, _orgDiskSides, _orgDiskHeaders);
 	
 	//Apply save data (saved as an IPS file), if found
@@ -69,7 +72,7 @@ void Fds::LoadDiskData(vector<uint8_t> ipsData)
 	_fdsDiskSides.clear();
 	_fdsDiskHeaders.clear();
 	
-	FdsLoader loader;
+	FdsLoader loader(_useQdFormat);
 	vector<uint8_t> patchedData;
 	if(ipsData.size() > 0 && IpsPatcher::PatchBuffer(ipsData, _fdsRawData, patchedData)) {
 		loader.LoadDiskData(patchedData, _fdsDiskSides, _fdsDiskHeaders);
@@ -80,9 +83,9 @@ void Fds::LoadDiskData(vector<uint8_t> ipsData)
 
 vector<uint8_t> Fds::CreateIpsPatch()
 {
-	FdsLoader loader;
+	FdsLoader loader(_useQdFormat);
 	bool needHeader = (memcmp(_fdsRawData.data(), "FDS\x1a", 4) == 0);
-	vector<uint8_t> newData = loader.RebuildFdsFile(_fdsDiskSides, needHeader);	
+	vector<uint8_t> newData = loader.RebuildFdsFile(_fdsDiskSides, needHeader);
 	return IpsPatcher::CreatePatch(_fdsRawData, newData);
 }
 
diff --git a/Core/NES/Mappers/FDS/Fds.h b/Core/NES/Mappers/FDS/Fds.h
index 3d42bd9a..e9ef12bd 100644
--- a/Core/NES/Mappers/FDS/Fds.h
+++ b/Core/NES/Mappers/FDS/Fds.h
@@ -67,6 +67,7 @@ private:
 	bool _gapEnded = true;
 	bool _scanningDisk = false;
 	bool _transferComplete = false;
+	bool _useQdFormat = false;
 	
 	vector<uint8_t> _fdsRawData;
 	vector<vector<uint8_t>> _fdsDiskSides;
diff --git a/Core/NES/NesConsole.h b/Core/NES/NesConsole.h
index 2c67b34b..a906d1b9 100644
--- a/Core/NES/NesConsole.h
+++ b/Core/NES/NesConsole.h
@@ -65,7 +65,7 @@ public:
 	NesConsole(Emulator* emulator);
 	~NesConsole();
 
-	static vector<string> GetSupportedExtensions() { return { ".nes", ".fds", ".unif", ".unf", ".nsf", ".nsfe", ".studybox" }; }
+	static vector<string> GetSupportedExtensions() { return { ".nes", ".fds", ".unif", ".unf", ".nsf", ".nsfe", ".studybox", ".qd" }; }
 	static vector<string> GetSupportedSignatures() { return { "NES\x1a", "FDS\x1a", "\x1*NINTENDO-HVC*", "NESM\x1a", "NSFE", "UNIF", "STBX" }; }
 
 	NesCpu* GetCpu() { return _cpu.get(); }
diff --git a/UI/Config/FileAssociationHelper.cs b/UI/Config/FileAssociationHelper.cs
index be20eb15..bcd40ceb 100644
--- a/UI/Config/FileAssociationHelper.cs
+++ b/UI/Config/FileAssociationHelper.cs
@@ -70,6 +70,7 @@ namespace Mesen.Config
 
 			CreateMimeType("x-mesen-nes", "nes", "NES ROM", mimeTypes, cfg.AssociateNesRomFiles);
 			CreateMimeType("x-mesen-fds", "fds", "FDS ROM", mimeTypes, cfg.AssociateNesRomFiles);
+			CreateMimeType("x-mesen-qd", "qd", "FDS ROM (QD format)", mimeTypes, cfg.AssociateNesRomFiles);
 			CreateMimeType("x-mesen-studybox", "studybox", "Studybox ROM (Famicom)", mimeTypes, cfg.AssociateNesRomFiles);
 			CreateMimeType("x-mesen-unif", "unf", "NES ROM", mimeTypes, cfg.AssociateNesRomFiles);
 
@@ -191,6 +192,7 @@ namespace Mesen.Config
 
 			FileAssociationHelper.UpdateFileAssociation("nes", cfg.AssociateNesRomFiles);
 			FileAssociationHelper.UpdateFileAssociation("fds", cfg.AssociateNesRomFiles);
+			FileAssociationHelper.UpdateFileAssociation("qd", cfg.AssociateNesRomFiles);
 			FileAssociationHelper.UpdateFileAssociation("unf", cfg.AssociateNesRomFiles);
 			FileAssociationHelper.UpdateFileAssociation("studybox", cfg.AssociateNesRomFiles);
 
diff --git a/UI/Localization/resources.en.xml b/UI/Localization/resources.en.xml
index 3b286f3d..20ae3d28 100644
--- a/UI/Localization/resources.en.xml
+++ b/UI/Localization/resources.en.xml
@@ -710,7 +710,7 @@
 			<Control ID="grpFileAssociations">File Associations</Control>
 			<Control ID="chkSnesRomFiles">SNES roms: .sfc, .smc, .swc, .fig, .bs</Control>
 			<Control ID="chkSnesMusicFiles">SNES music: .spc</Control>
-			<Control ID="chkNesRomFiles">NES roms: .nes, .unif, .fds, .studybox</Control>
+			<Control ID="chkNesRomFiles">NES roms: .nes, .unif, .fds, .qd, .studybox</Control>
 			<Control ID="chkNesMusicFiles">NES music: .nsf, .nsfe</Control>
 			<Control ID="chkGbRomFiles">Game Boy roms: .gb, .gbc, .gbx</Control>
 			<Control ID="chkGbMusicFiles">Game Boy music: .gbs</Control>
diff --git a/UI/Utilities/FileDialogHelper.cs b/UI/Utilities/FileDialogHelper.cs
index 564d22ab..c47e1898 100644
--- a/UI/Utilities/FileDialogHelper.cs
+++ b/UI/Utilities/FileDialogHelper.cs
@@ -53,7 +53,7 @@ namespace Mesen.Utilities
 					if(ext == FileDialogHelper.RomExt) {
 						filter.Add(new FilePickerFileType("All ROM files") { Patterns = new List<string>() { 
 							"*.sfc", "*.fig", "*.smc", "*.bs", "*.st", "*.spc",
-							"*.nes", "*.fds", "*.unif", "*.unf", "*.studybox", "*.nsf", "*.nsfe",
+							"*.nes", "*.fds", "*.qd", "*.unif", "*.unf", "*.studybox", "*.nsf", "*.nsfe",
 							"*.gb", "*.gbc", "*.gbx", "*.gbs",
 							"*.pce", "*.sgx", "*.cue", "*.hes",
 							"*.sms", "*.gg", "*.sg", "*.col",
@@ -62,7 +62,7 @@ namespace Mesen.Utilities
 							"*.zip", "*.7z"
 						} });
 						filter.Add(new FilePickerFileType("SNES ROM files") { Patterns = new List<string>() { "*.sfc", "*.fig", "*.smc", "*.bs", "*.st", "*.spc" } });
-						filter.Add(new FilePickerFileType("NES ROM files") { Patterns = new List<string>() { "*.nes", "*.fds", "*.unif", "*.unf", "*.studybox", "*.nsf", "*.nsfe" } });
+						filter.Add(new FilePickerFileType("NES ROM files") { Patterns = new List<string>() { "*.nes", "*.fds", "*.qd", "*.unif", "*.unf", "*.studybox", "*.nsf", "*.nsfe" } });
 						filter.Add(new FilePickerFileType("GB ROM files") { Patterns = new List<string>() { "*.gb", "*.gbc", "*.gbx", "*.gbs" } });
 						filter.Add(new FilePickerFileType("GBA ROM files") { Patterns = new List<string>() { "*.gba" } });
 						filter.Add(new FilePickerFileType("PC Engine ROM files") { Patterns = new List<string>() { "*.pce", "*.sgx", "*.cue", "*.hes" } });
diff --git a/UI/Utilities/FolderHelper.cs b/UI/Utilities/FolderHelper.cs
index bdebbe98..0d64c644 100644
--- a/UI/Utilities/FolderHelper.cs
+++ b/UI/Utilities/FolderHelper.cs
@@ -13,7 +13,7 @@ namespace Mesen.Utilities
 		private static HashSet<string> _romExtensions = new HashSet<string>() {
 			".sfc", ".smc", ".fig", ".swc", ".bs", ".st",
 			".gb", ".gbc", ".gbx",
-			".nes", ".unif", ".unf", ".fds", ".studybox",
+			".nes", ".unif", ".unf", ".fds", ".qd", ".studybox",
 			".pce", ".sgx", ".cue",
 			".sms", ".gg", ".sg", ".col",
 			".gba",
diff --git a/Utilities/StringUtilities.h b/Utilities/StringUtilities.h
index 8e4e04fa..22997bc7 100644
--- a/Utilities/StringUtilities.h
+++ b/Utilities/StringUtilities.h
@@ -65,6 +65,10 @@ public:
 	static bool StartsWith(string& str, const char* content)
 	{
 		size_t length = strlen(content);
+		if(str.size() < length) {
+			return false;
+		}
+
 		for(size_t i = 0; i < length; i++) {
 			if(str[i] != content[i]) {
 				return false;
@@ -72,7 +76,24 @@ public:
 		}
 		return true;
 	}
-	
+
+	static bool EndsWith(string& str, const char* content)
+	{
+		size_t length = strlen(content);
+		if(str.size() < length) {
+			return false;
+		}
+
+		size_t startPos = str.size() - length;
+		for(size_t i = startPos; i < str.size(); i++) {
+			if(str[i] != content[i - startPos]) {
+				return false;
+			}
+		}
+
+		return true;
+	}
+
 	static bool Contains(string& str, const char* content)
 	{
 		size_t length = strlen(content);
diff --git a/Utilities/VirtualFile.cpp b/Utilities/VirtualFile.cpp
index a8dfb8f3..99a1e837 100644
--- a/Utilities/VirtualFile.cpp
+++ b/Utilities/VirtualFile.cpp
@@ -12,7 +12,7 @@
 #include "Utilities/CRC32.h"
 
 const std::initializer_list<string> VirtualFile::RomExtensions = {
-	".nes", ".fds", ".unif", ".unf", ".nsf", ".nsfe", ".studybox",
+	".nes", ".fds", ".qd", ".unif", ".unf", ".nsf", ".nsfe", ".studybox",
 	".sfc", ".swc", ".fig", ".smc", ".bs", ".st", ".spc",
 	".gb", ".gbc", ".gbx", ".gbs",
 	".pce", ".sgx", ".cue", ".hes",