diff --git a/src/BizHawk.Client.Common/Api/Classes/EmulationApi.cs b/src/BizHawk.Client.Common/Api/Classes/EmulationApi.cs
index 7ae6b0e335..35b26b5144 100644
--- a/src/BizHawk.Client.Common/Api/Classes/EmulationApi.cs
+++ b/src/BizHawk.Client.Common/Api/Classes/EmulationApi.cs
@@ -1,4 +1,6 @@
-using System;
+#nullable enable
+
+using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 
@@ -20,29 +22,29 @@ namespace BizHawk.Client.Common
 	public sealed class EmulationApi : IEmulationApi
 	{
 		[RequiredService]
-		private IEmulator Emulator { get; set; }
+		private IEmulator? Emulator { get; set; }
 
 		[OptionalService]
-		private IBoardInfo BoardInfo { get; set; }
+		private IBoardInfo? BoardInfo { get; set; }
 
 		[OptionalService]
-		private IDebuggable DebuggableCore { get; set; }
+		private IDebuggable? DebuggableCore { get; set; }
 
 		[OptionalService]
-		private IDisassemblable DisassemblableCore { get; set; }
+		private IDisassemblable? DisassemblableCore { get; set; }
 
 		[OptionalService]
-		private IInputPollable InputPollableCore { get; set; }
+		private IInputPollable? InputPollableCore { get; set; }
 
 		[OptionalService]
-		private IMemoryDomains MemoryDomains { get; set; }
+		private IMemoryDomains? MemoryDomains { get; set; }
 
 		[OptionalService]
-		private IRegionable RegionableCore { get; set; }
+		private IRegionable? RegionableCore { get; set; }
 
 		private readonly Config _config;
 
-		private readonly IGameInfo _game;
+		private readonly IGameInfo? _game;
 
 		private readonly Action<string> LogCallback;
 
@@ -58,7 +60,7 @@ namespace BizHawk.Client.Common
 
 		public bool ForbiddenConfigReferenceUsed { get; private set; }
 
-		public EmulationApi(Action<string> logCallback, Config config, IGameInfo game)
+		public EmulationApi(Action<string> logCallback, Config config, IGameInfo? game)
 		{
 			_config = config;
 			_game = game;
@@ -67,9 +69,10 @@ namespace BizHawk.Client.Common
 
 		public void DisplayVsync(bool enabled) => _config.VSync = enabled;
 
-		public int FrameCount() => Emulator.Frame;
+		public int FrameCount()
+			=> Emulator!.Frame;
 
-		public object Disassemble(uint pc, string name = "")
+		public object? Disassemble(uint pc, string? name = null)
 		{
 			try
 			{
@@ -77,7 +80,7 @@ namespace BizHawk.Client.Common
 				{
 					return new {
 						disasm = DisassemblableCore.Disassemble(
-							string.IsNullOrEmpty(name) ? MemoryDomains.SystemBus : MemoryDomains[name]!,
+							string.IsNullOrEmpty(name) ? MemoryDomains!.SystemBus : MemoryDomains![name!]!,
 							pc,
 							out var l
 						),
@@ -97,7 +100,7 @@ namespace BizHawk.Client.Common
 				if (DebuggableCore != null)
 				{
 					var registers = DebuggableCore.GetCpuFlagsAndRegisters();
-					return registers.TryGetValue(name, out var rv) ? rv.Value : (ulong?) null;
+					return registers.TryGetValue(name, out var rv) ? rv.Value : null;
 				}
 			}
 			catch (NotImplementedException) {}
@@ -146,7 +149,8 @@ namespace BizHawk.Client.Common
 			return default;
 		}
 
-		public string GetSystemId() => _game.System;
+		public string GetSystemId()
+			=> _game!.System;
 
 		public bool IsLagged()
 		{
@@ -182,7 +186,7 @@ namespace BizHawk.Client.Common
 
 		public string GetBoardName() => BoardInfo?.BoardName ?? "";
 
-		public object GetSettings() => Emulator switch
+		public object? GetSettings() => Emulator switch
 		{
 			GPGX gpgx => gpgx.GetSettings(),
 			LibsnesCore snes => snes.GetSettings(),
diff --git a/src/BizHawk.Client.Common/Api/Interfaces/IEmulationApi.cs b/src/BizHawk.Client.Common/Api/Interfaces/IEmulationApi.cs
index f2eb833f49..760ae2fee7 100644
--- a/src/BizHawk.Client.Common/Api/Interfaces/IEmulationApi.cs
+++ b/src/BizHawk.Client.Common/Api/Interfaces/IEmulationApi.cs
@@ -1,4 +1,6 @@
-using System.Collections.Generic;
+#nullable enable
+
+using System.Collections.Generic;
 
 using BizHawk.Emulation.Common;
 
@@ -8,7 +10,7 @@ namespace BizHawk.Client.Common
 	{
 		void DisplayVsync(bool enabled);
 		int FrameCount();
-		object Disassemble(uint pc, string name = "");
+		object? Disassemble(uint pc, string? name = null);
 		ulong? GetRegister(string name);
 		IReadOnlyDictionary<string, ulong> GetRegisters();
 		void SetRegister(string register, int value);
@@ -22,7 +24,7 @@ namespace BizHawk.Client.Common
 		void MinimizeFrameskip(bool enabled);
 		string GetDisplayType();
 		string GetBoardName();
-		object GetSettings();
+		object? GetSettings();
 		PutSettingsDirtyBits PutSettings(object settings);
 		void SetRenderPlanes(params bool[] args);
 	}