diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
index 7e4b2b2d0c..0e63b179b4 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
@@ -372,6 +372,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 			if (!LibGPGX.gpgx_get_control(input, inputsize))
 				throw new Exception("gpgx_get_control() failed!");
 
+			ControlConverter.ScreenWidth = vwidth;
+			ControlConverter.ScreenHeight = vheight;
 			ControlConverter.Convert(Controller, input);
 
 			if (!LibGPGX.gpgx_put_control(input, inputsize))
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGXControlConverter.cs b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGXControlConverter.cs
index 7180d9c388..2b65c93c58 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGXControlConverter.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGXControlConverter.cs
@@ -66,8 +66,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 		};
 
 		static ControllerDefinition.FloatRange MouseRange = new ControllerDefinition.FloatRange(-512, 0, 511);
-		static ControllerDefinition.FloatRange LightgunX = new ControllerDefinition.FloatRange(0, 160, 319);
-		static ControllerDefinition.FloatRange LightgunY = new ControllerDefinition.FloatRange(0, 112, 223);
+		// lightgun needs to be transformed to match the current screen resolution
+		static ControllerDefinition.FloatRange LightgunRange = new ControllerDefinition.FloatRange(0, 5000, 10000);
 
 		LibGPGX.InputData target = null;
 		IController source = null;
@@ -112,12 +112,12 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 			string NY = string.Format("P{0} Lightgun Y", player);
 			ControllerDef.FloatControls.Add(NX);
 			ControllerDef.FloatControls.Add(NY);
-			ControllerDef.FloatRanges.Add(LightgunX);
-			ControllerDef.FloatRanges.Add(LightgunY);
+			ControllerDef.FloatRanges.Add(LightgunRange);
+			ControllerDef.FloatRanges.Add(LightgunRange);
 			Converts.Add(delegate()
 			{
-				target.analog[(2 * idx) + 0] = (short)source.GetFloat(NX);
-				target.analog[(2 * idx) + 1] = (short)source.GetFloat(NY);
+				target.analog[(2 * idx) + 0] = (short)(source.GetFloat(NX) / 10000.0f * (ScreenWidth - 1));
+				target.analog[(2 * idx) + 1] = (short)(source.GetFloat(NY) / 10000.0f * (ScreenHeight - 1));
 			});
 		}
 
@@ -180,5 +180,14 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 			this.target = null;
 		}
 
+		/// <summary>
+		/// must be set for proper lightgun operation
+		/// </summary>
+		public int ScreenWidth { get; set; }
+		/// <summary>
+		/// must be set for proper lightgun operation
+		/// </summary>
+		public int ScreenHeight { get; set; }
+
 	}
 }