diff --git a/src/BizHawk.Tests.Testroms.GB.GambatteSuite/GambatteSuite.cs b/src/BizHawk.Tests.Testroms.GB.GambatteSuite/GambatteSuite.cs
index 884f0ca03b..bd576a05c7 100644
--- a/src/BizHawk.Tests.Testroms.GB.GambatteSuite/GambatteSuite.cs
+++ b/src/BizHawk.Tests.Testroms.GB.GambatteSuite/GambatteSuite.cs
@@ -139,7 +139,7 @@ namespace BizHawk.Tests.Testroms.GB.GambatteSuite
 		{
 			static bool GlyphMatches(Bitmap b, int xOffset, byte v)
 			{
-				// `(x, 0)` is the top-left of an 8x8 square of pixels to read from `b`, which is compared against the glyph for the nybble `v`
+				// `(xOffset, 0)` is the top-left of an 8x8 square of pixels to read from `b`, which is compared against the glyph for the nybble `v`
 				bool GlyphRowMatches(int y)
 				{
 					byte rowAsByte = 0;
diff --git a/src/BizHawk.Tests.Testroms.GB/GB_GBC/GBHelper.cs b/src/BizHawk.Tests.Testroms.GB/GB_GBC/GBHelper.cs
index b598469ee4..e4b23bba0e 100644
--- a/src/BizHawk.Tests.Testroms.GB/GB_GBC/GBHelper.cs
+++ b/src/BizHawk.Tests.Testroms.GB/GB_GBC/GBHelper.cs
@@ -37,17 +37,17 @@ namespace BizHawk.Tests.Testroms.GB
 				Variant = variant;
 			}
 
-			public override readonly string ToString()
+			public readonly override string ToString()
 				=> $"{Variant} in {CoreName}{(UseBIOS ? string.Empty : " (no BIOS)")}";
 		}
 
 		private static readonly GambatteSettings GambatteSettings = new() { CGBColors = GBColors.ColorType.vivid };
 
-		private static readonly GambatteSyncSettings GambatteSyncSettings_GB_NOBIOS = new() { ConsoleMode = GambatteSyncSettings.ConsoleModeType.GB, FrameLength = GambatteSyncSettings.FrameLengthType.EqualLengthFrames };
+		private static readonly GambatteSyncSettings GambatteSyncSettings_GB_NOBIOS = new() { ConsoleMode = GambatteSyncSettings.ConsoleModeType.GB, EnableBIOS = false, FrameLength = GambatteSyncSettings.FrameLengthType.EqualLengthFrames };
 
 		private static readonly GambatteSyncSettings GambatteSyncSettings_GB_USEBIOS = new() { ConsoleMode = GambatteSyncSettings.ConsoleModeType.GB, EnableBIOS = true, FrameLength = GambatteSyncSettings.FrameLengthType.EqualLengthFrames };
 
-		private static readonly GambatteSyncSettings GambatteSyncSettings_GBC_NOBIOS = new() { ConsoleMode = GambatteSyncSettings.ConsoleModeType.GBC, FrameLength = GambatteSyncSettings.FrameLengthType.EqualLengthFrames };
+		private static readonly GambatteSyncSettings GambatteSyncSettings_GBC_NOBIOS = new() { ConsoleMode = GambatteSyncSettings.ConsoleModeType.GBC, EnableBIOS = false, FrameLength = GambatteSyncSettings.FrameLengthType.EqualLengthFrames };
 
 		private static readonly GambatteSyncSettings GambatteSyncSettings_GBC_USEBIOS = new() { ConsoleMode = GambatteSyncSettings.ConsoleModeType.GBC, EnableBIOS = true, FrameLength = GambatteSyncSettings.FrameLengthType.EqualLengthFrames };
 
@@ -117,13 +117,9 @@ namespace BizHawk.Tests.Testroms.GB
 		}
 
 		public static GambatteSyncSettings GetGambatteSyncSettings(ConsoleVariant variant, bool biosAvailable)
-			=> biosAvailable
-				? variant.IsColour()
-					? GambatteSyncSettings_GBC_USEBIOS
-					: GambatteSyncSettings_GB_USEBIOS
-				: variant.IsColour()
-					? GambatteSyncSettings_GBC_NOBIOS
-					: GambatteSyncSettings_GB_NOBIOS;
+			=> variant.IsColour()
+				? biosAvailable ? GambatteSyncSettings_GBC_USEBIOS : GambatteSyncSettings_GBC_NOBIOS
+				: biosAvailable ? GambatteSyncSettings_GB_USEBIOS : GambatteSyncSettings_GB_NOBIOS;
 
 		public static GBSyncSettings GetGBHawkSyncSettings(ConsoleVariant variant)
 			=> variant.IsColour()
@@ -154,8 +150,10 @@ namespace BizHawk.Tests.Testroms.GB
 
 		/// <summary>converts Gambatte's GBC palette to GBHawk's; GB palette is the same</summary>
 		public static Image NormaliseGBScreenshot(Image img, CoreSetup setup)
-			=> setup.CoreName is CoreNames.Gambatte
-				? ImageUtils.PaletteSwap(img, setup.Variant.IsColour() ? UnVividGBCPaletteMap : UnVividGBPaletteMap)
-				: img;
+			=> setup.CoreName switch
+			{
+				CoreNames.Gambatte => ImageUtils.PaletteSwap(img, setup.Variant.IsColour() ? UnVividGBCPaletteMap : UnVividGBPaletteMap),
+				_ => img
+			};
 	}
 }
diff --git a/src/BizHawk.Tests.Testroms.GB/GB_GBC/MealybugTearoomTests.cs b/src/BizHawk.Tests.Testroms.GB/GB_GBC/MealybugTearoomTests.cs
index 56eca59731..55c18d80e7 100644
--- a/src/BizHawk.Tests.Testroms.GB/GB_GBC/MealybugTearoomTests.cs
+++ b/src/BizHawk.Tests.Testroms.GB/GB_GBC/MealybugTearoomTests.cs
@@ -7,7 +7,6 @@ using BizHawk.Common.IOExtensions;
 using BizHawk.Common.StringExtensions;
 using BizHawk.Emulation.Common;
 using BizHawk.Emulation.Cores;
-using BizHawk.Emulation.Cores.Nintendo.Gameboy;
 using BizHawk.Emulation.Cores.Nintendo.GBHawk;
 
 using Microsoft.VisualStudio.TestTools.UnitTesting;
@@ -218,13 +217,12 @@ namespace BizHawk.Tests.Testroms.GB
 					fe.FrameAdvanceBy(5);
 					if (testCase.TestName is "m3_lcdc_win_map_change2") fe.FrameAdvance(); // just happens to be an outlier
 				}
-				var domain = fe.CoreAsMemDomains!.SystemBus;
-				Func<long> derefPC = fe.Core switch
+				Func<long> getPC = fe.Core switch
 				{
-					Gameboy => () => domain.PeekByte((long) fe.CoreAsDebuggable!.GetCpuFlagsAndRegisters()["PC"].Value),
-					GBHawk gbHawk => () => domain.PeekByte(gbHawk.cpu.RegPC),
-					_ => throw new Exception()
+					GBHawk gbHawk => () => gbHawk.cpu.RegPC,
+					_ => () => (long) fe.CoreAsDebuggable!.GetCpuFlagsAndRegisters()["PC"].Value
 				};
+				var domain = fe.CoreAsMemDomains!.SystemBus;
 				var finished = false;
 				fe.CoreAsDebuggable!.MemoryCallbacks.Add(new MemoryCallback(
 					domain.Name,
@@ -232,7 +230,7 @@ namespace BizHawk.Tests.Testroms.GB
 					"breakpoint",
 					(_, _, _) =>
 					{
-						if (!finished && derefPC() is 0x40) finished = true;
+						if (!finished && domain.PeekByte(getPC()) is 0x40) finished = true;
 					},
 					address: null, // all addresses
 					mask: null));
diff --git a/src/BizHawk.Tests.Testroms.GB/ImageUtils.cs b/src/BizHawk.Tests.Testroms.GB/ImageUtils.cs
index cab0d57f18..0db88f362d 100644
--- a/src/BizHawk.Tests.Testroms.GB/ImageUtils.cs
+++ b/src/BizHawk.Tests.Testroms.GB/ImageUtils.cs
@@ -21,7 +21,7 @@ namespace BizHawk.Tests.Testroms.GB
 		private static (string Expect, string Actual, string Glob) GenFilenames((string Suite, string Case) id, string fileExt = "png")
 		{
 			var prefix = $"{id.Suite}/{id.Case.GetHashCode():X8}"; // hashcode of string sadly not stable
-			var suffix = $"{id.Case.RemoveInvalidFileSystemChars().Replace(' ', '_')}.{fileExt}";
+			var suffix = $"{id.Case.RemoveInvalidFileSystemChars().Replace(' ', '_').Replace("(no BIOS)", "noBIOS")}.{fileExt}";
 			return ($"{prefix}_expect_{suffix}", $"{prefix}_actual_{suffix}", $"{prefix}_*_{suffix}");
 		}