diff --git a/src/BizHawk.Emulation.Cores/Consoles/Atari/Stella/LibStella.cs b/src/BizHawk.Emulation.Cores/Consoles/Atari/Stella/LibStella.cs
index c05d87d2bd..8b7e0eb654 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Atari/Stella/LibStella.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Atari/Stella/LibStella.cs
@@ -28,7 +28,7 @@ namespace BizHawk.Emulation.Cores.Atari.Stella
 			[In] InitSettings settings);
 
 		[BizImport(CallingConvention.Cdecl)]
-		public abstract void stella_frame_advance(int port1, int port2, bool reset, bool power, bool leftDiffToggled, bool rightDiffToggled);
+		public abstract void stella_frame_advance(byte port1, byte port2, bool reset, bool power, bool leftDiffToggled, bool rightDiffToggled);
 
 		[BizImport(CallingConvention.Cdecl)]
 		public abstract void stella_get_video(out int w, out int h, out int pitch, ref IntPtr buffer);
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Atari/Stella/Stella.IEmulator.cs b/src/BizHawk.Emulation.Cores/Consoles/Atari/Stella/Stella.IEmulator.cs
index 4eb21a32f6..a356fe9687 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Atari/Stella/Stella.IEmulator.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Atari/Stella/Stella.IEmulator.cs
@@ -13,8 +13,8 @@ namespace BizHawk.Emulation.Cores.Atari.Stella
 
 		public bool FrameAdvance(IController controller, bool render, bool renderSound)
 		{
-			int port1 = _controllerDeck.ReadPort1(controller);
-			int port2 = _controllerDeck.ReadPort2(controller);
+			byte port1 = _controllerDeck.ReadPort1(controller);
+			byte port2 = _controllerDeck.ReadPort2(controller);
             
 			// Handle all the console controls here
 			bool powerPressed = false;