diff --git a/src/BizHawk.Emulation.Cores/Consoles/NEC/PCE/HyperNyma.cs b/src/BizHawk.Emulation.Cores/Consoles/NEC/PCE/HyperNyma.cs
index 3ba961c73b..cf2f57d1c8 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/NEC/PCE/HyperNyma.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/NEC/PCE/HyperNyma.cs
@@ -41,14 +41,14 @@ namespace BizHawk.Emulation.Cores.Consoles.NEC.PCE
 		public HyperNyma(CoreLoadParameters<NymaSettings, NymaSyncSettings> lp)
 			: base(lp.Comm, VSystemID.Raw.PCE, "PC Engine Controller", lp.Settings, lp.SyncSettings)
 		{
-			var firmwares = new Dictionary<string, FirmwareID>();
+			var firmwareIDMap = new Dictionary<string, FirmwareID>();
 			if (lp.Discs.Count > 0)
 			{
 				_hasCds = true;
-				firmwares.Add("FIRMWARE:syscard3.pce", new("PCECD", "Bios"));
+				firmwareIDMap.Add("FIRMWARE:syscard3.pce", new("PCECD", "Bios"));
 			}
 
-			_hyperNyma = DoInit<LibHyperNyma>(lp, "hyper.wbx", firmwares);
+			_hyperNyma = DoInit<LibHyperNyma>(lp, "hyper.wbx", firmwareIDMap);
 
 			_cachedSettingsInfo ??= SettingsInfo.Clone();
 		}
diff --git a/src/BizHawk.Emulation.Cores/Consoles/NEC/PCE/TurboNyma.cs b/src/BizHawk.Emulation.Cores/Consoles/NEC/PCE/TurboNyma.cs
index ca7cb4b3fa..d624de3240 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/NEC/PCE/TurboNyma.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/NEC/PCE/TurboNyma.cs
@@ -43,15 +43,15 @@ namespace BizHawk.Emulation.Cores.Consoles.NEC.PCE
 		public TurboNyma(CoreLoadParameters<NymaSettings, NymaSyncSettings> lp)
 			: base(lp.Comm, VSystemID.Raw.PCE, "PC Engine Controller", lp.Settings, lp.SyncSettings)
 		{
-			var firmwares = new Dictionary<string, FirmwareID>();
+			var firmwareIDMap = new Dictionary<string, FirmwareID>();
 			if (lp.Discs.Count > 0)
 			{
 				_hasCds = true;
 				var ids = lp.Discs.Select(dg => dg.DiscType).ToList();
 				if (ids.Contains(DiscType.TurboCD))
-					firmwares.Add("FIRMWARE:syscard3.pce", new("PCECD", "Bios"));
+					firmwareIDMap.Add("FIRMWARE:syscard3.pce", new("PCECD", "Bios"));
 				if (ids.Contains(DiscType.TurboGECD))
-					firmwares.Add("FIRMWARE:gecard.pce", new("PCECD", "GE-Bios"));
+					firmwareIDMap.Add("FIRMWARE:gecard.pce", new("PCECD", "GE-Bios"));
 			}
 			else if (lp.Roms.Count == 1)
 			{
@@ -59,7 +59,7 @@ namespace BizHawk.Emulation.Cores.Consoles.NEC.PCE
 					SettingOverrides["pce.disable_bram_hucard"].Default = "0";
 			}
 
-			_turboNyma = DoInit<LibTurboNyma>(lp, "turbo.wbx", firmwares);
+			_turboNyma = DoInit<LibTurboNyma>(lp, "turbo.wbx", firmwareIDMap);
 
 			_cachedSettingsInfo ??= SettingsInfo.Clone();
 		}
diff --git a/src/BizHawk.Emulation.Cores/Consoles/NEC/PCFX/Tst.cs b/src/BizHawk.Emulation.Cores/Consoles/NEC/PCFX/Tst.cs
index 8d72904ee4..9fc62224de 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/NEC/PCFX/Tst.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/NEC/PCFX/Tst.cs
@@ -33,12 +33,12 @@ namespace BizHawk.Emulation.Cores.Consoles.NEC.PCFX
 		{
 			if (lp.Roms.Count > 0)
 				throw new InvalidOperationException("To load a PC-FX game, please load the CUE file and not the BIN file.");
-			var firmwares = new Dictionary<string, FirmwareID>
+			var firmwareIDMap = new Dictionary<string, FirmwareID>
 			{
 				{ "FIRMWARE:pcfx.rom", new("PCFX", "BIOS") },
 			};
 
-			DoInit<LibNymaCore>(lp, "pcfx.wbx", firmwares);
+			DoInit<LibNymaCore>(lp, "pcfx.wbx", firmwareIDMap);
 
 			_cachedSettingsInfo ??= SettingsInfo.Clone();
 		}
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Sega/Saturn/Saturnus.cs b/src/BizHawk.Emulation.Cores/Consoles/Sega/Saturn/Saturnus.cs
index 6169012aeb..4fbb988a1b 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Sega/Saturn/Saturnus.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Sega/Saturn/Saturnus.cs
@@ -35,7 +35,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.Saturn
 		{
 			if (lp.Roms.Count > 0)
 				throw new InvalidOperationException("To load a Saturn game, please load the CUE file and not the BIN file.");
-			var firmwares = new Dictionary<string, FirmwareID>
+			var firmwareIDMap = new Dictionary<string, FirmwareID>
 			{
 				{ "FIRMWARE:$J", new("SAT", "J") },
 				{ "FIRMWARE:$U", new("SAT", "U") },
@@ -43,7 +43,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.Saturn
 				{ "FIRMWARE:$ULTRA", new("SAT", "ULTRAMAN") },
 				// { "FIRMWARE:$SATAR", new("SAT", "AR") }, // action replay garbage
 			};
-			_saturnus = DoInit<LibSaturnus>(lp, "ss.wbx", firmwares);
+			_saturnus = DoInit<LibSaturnus>(lp, "ss.wbx", firmwareIDMap);
 
 			_cachedSettingsInfo ??= SettingsInfo.Clone();
 		}
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Sony/PSX/Nymashock.cs b/src/BizHawk.Emulation.Cores/Consoles/Sony/PSX/Nymashock.cs
index 5442f218ee..532d781c79 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Sony/PSX/Nymashock.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Sony/PSX/Nymashock.cs
@@ -61,13 +61,13 @@ namespace BizHawk.Emulation.Cores.Sony.PSX
 		public Nymashock(CoreLoadParameters<NymaSettings, NymaSyncSettings> lp)
 			: base(lp.Comm, VSystemID.Raw.PSX, "PSX Front Panel", lp.Settings, lp.SyncSettings)
 		{
-			var firmwares = new Dictionary<string, FirmwareID>
+			var firmwareIDMap = new Dictionary<string, FirmwareID>
 			{
 				{ "FIRMWARE:$J", new("PSX", "J") },
 				{ "FIRMWARE:$U", new("PSX", "U") },
 				{ "FIRMWARE:$E", new("PSX", "E") },
 			};
-			DoInit<LibNymaCore>(lp, "shock.wbx", firmwares);
+			DoInit<LibNymaCore>(lp, "shock.wbx", firmwareIDMap);
 
 			_cachedSettingsInfo ??= SettingsInfo.Clone();
 
diff --git a/src/BizHawk.Emulation.Cores/Waterbox/NymaCore.cs b/src/BizHawk.Emulation.Cores/Waterbox/NymaCore.cs
index 11cd4045b4..3720188c96 100644
--- a/src/BizHawk.Emulation.Cores/Waterbox/NymaCore.cs
+++ b/src/BizHawk.Emulation.Cores/Waterbox/NymaCore.cs
@@ -48,7 +48,7 @@ namespace BizHawk.Emulation.Cores.Waterbox
 		protected T DoInit<T>(
 			CoreLoadParameters<NymaSettings, NymaSyncSettings> lp,
 			string wbxFilename,
-			IDictionary<string, FirmwareID> firmwares = null
+			IDictionary<string, FirmwareID> firmwareIDMap = null
 		)
 			where T : LibNymaCore
 		{
@@ -59,11 +59,11 @@ namespace BizHawk.Emulation.Cores.Waterbox
 				wbxFilename,
 				lp.Roms.FirstOrDefault()?.Extension,
 				lp.DeterministicEmulationRequested,
-				firmwares
+				firmwareIDMap
 			);
 		}
 		protected T DoInit<T>(GameInfo game, byte[] rom, Disc[] discs, string wbxFilename, string extension, bool deterministic,
-			IDictionary<string, FirmwareID> firmwares = null)
+			IDictionary<string, FirmwareID> firmwareIDMap = null)
 			where T : LibNymaCore
 		{
 			_settingsQueryDelegate = SettingsQuery;
@@ -74,7 +74,7 @@ namespace BizHawk.Emulation.Cores.Waterbox
 
 			var firmwareDelegate = new LibNymaCore.FrontendFirmwareNotify((name) =>
 			{
-				if (firmwares != null && firmwares.TryGetValue(name, out var id))
+				if (firmwareIDMap != null && firmwareIDMap.TryGetValue(name, out var id))
 				{
 					var data = CoreComm.CoreFileProvider.GetFirmwareOrThrow(id, "Firmware files are usually required and may stop your game from loading");
 					_exe.AddReadonlyFile(data, name);