diff --git a/GUI.NET/Forms/Config/frmVideoConfig.Designer.cs b/GUI.NET/Forms/Config/frmVideoConfig.Designer.cs
index 1b66ac9f..5f4177eb 100644
--- a/GUI.NET/Forms/Config/frmVideoConfig.Designer.cs
+++ b/GUI.NET/Forms/Config/frmVideoConfig.Designer.cs
@@ -291,7 +291,8 @@ namespace Mesen.GUI.Forms.Config
             "1280x720",
             "1152x864",
             "1024x768",
-            "800x600"});
+            "800x600",
+            "640x480"});
 			this.cboFullscreenResolution.Location = new System.Drawing.Point(120, 3);
 			this.cboFullscreenResolution.Name = "cboFullscreenResolution";
 			this.cboFullscreenResolution.Size = new System.Drawing.Size(85, 21);
diff --git a/GUI.NET/Forms/frmMain.cs b/GUI.NET/Forms/frmMain.cs
index 879d4c9f..cd5a6d31 100644
--- a/GUI.NET/Forms/frmMain.cs
+++ b/GUI.NET/Forms/frmMain.cs
@@ -401,6 +401,10 @@ namespace Mesen.GUI.Forms
 
 		private void UpdateViewerSize(bool forceUpdate = false)
 		{
+			if(_frmFullscreenRenderer != null) {
+				return;
+			}
+
 			this.Resize -= frmMain_Resize;
 
 			InteropEmu.ScreenSize size = InteropEmu.GetScreenSize(false);
@@ -531,6 +535,9 @@ namespace Mesen.GUI.Forms
 		private void StartExclusiveFullscreenMode()
 		{
 			Size screenSize = GetFullscreenResolution();
+			Size originalWindowSize = this.Size;
+			double originalScale = ConfigManager.Config.VideoInfo.VideoScale;
+			this.Resize -= frmMain_Resize;
 
 			_frmFullscreenRenderer = new frmFullscreenRenderer();
 			_frmFullscreenRenderer.Shown += (object sender, EventArgs e) => {
@@ -540,16 +547,20 @@ namespace Mesen.GUI.Forms
 			};
 			_frmFullscreenRenderer.FormClosing += (object sender, FormClosingEventArgs e) => {
 				InteropEmu.SetFullscreenMode(false, ctrlRenderer.Handle, (UInt32)screenSize.Width, (UInt32)screenSize.Height);
+				this.Resize += frmMain_Resize;
 				_frmFullscreenRenderer = null;
 				ctrlRenderer.Visible = true;
 				_fullscreenMode = false;
-				frmMain_Resize(null, EventArgs.Empty);
+
+				this.SetScale(originalScale);
+				this.Size = originalWindowSize;
 			};
 
 			Screen currentScreen = Screen.FromHandle(this.Handle);
 			_frmFullscreenRenderer.StartPosition = FormStartPosition.Manual;
 			_frmFullscreenRenderer.Top = currentScreen.Bounds.Top;
 			_frmFullscreenRenderer.Left = currentScreen.Bounds.Left;
+			_frmFullscreenRenderer.Size = screenSize;
 			_frmFullscreenRenderer.Show();
 		}
 
@@ -778,6 +789,10 @@ namespace Mesen.GUI.Forms
 
 		private void ProcessResolutionChanged()
 		{
+			if(_frmFullscreenRenderer != null) {
+				return;
+			}
+
 			//Force scale specified by command line options, when using /fullscreen
 			if(_fullscreenRequested) {
 				SetFullscreenState(true);
diff --git a/Windows/Renderer.cpp b/Windows/Renderer.cpp
index 7f673ca7..0cf7a85b 100644
--- a/Windows/Renderer.cpp
+++ b/Windows/Renderer.cpp
@@ -71,6 +71,16 @@ void Renderer::SetScreenSize(uint32_t width, uint32_t height)
 			if(_fullscreen) {
 				_realScreenHeight = _monitorHeight;
 				_realScreenWidth = _monitorWidth;
+
+				if(_monitorHeight < _screenHeight || _monitorWidth < _screenWidth) {
+					double scale = (double)screenSize.Width / (double)screenSize.Height;
+					_screenHeight = _monitorHeight;
+					_screenWidth = (uint32_t)(scale * _screenHeight);
+					if(_monitorWidth < _screenWidth) {
+						_screenWidth = _monitorWidth;
+						_screenHeight = (uint32_t)(_screenWidth / scale);
+					}
+				}
 			} else {
 				_realScreenHeight = screenSize.Height;
 				_realScreenWidth = screenSize.Width;