diff --git a/src/BizHawk.Client.Common/movie/MovieService.cs b/src/BizHawk.Client.Common/movie/MovieService.cs
index cadd22bd4a..b283cb0715 100644
--- a/src/BizHawk.Client.Common/movie/MovieService.cs
+++ b/src/BizHawk.Client.Common/movie/MovieService.cs
@@ -18,11 +18,11 @@ namespace BizHawk.Client.Common
 		}
 
 		/// <summary>
-		/// Creates a <see cref="ITasSession"/> instance
+		/// Creates a <see cref="ITasMovie"/> instance
 		/// </summary>
-		public static ITasMovie CreateTas(bool startsFromSavestate = false)
+		public static ITasMovie CreateTas(string filename, bool startsFromSavestate = false)
 		{
-			return new TasMovie(startsFromSavestate: startsFromSavestate);
+			return new TasMovie(filename, startsFromSavestate);
 		}
 
 		public static string StandardMovieExtension => Bk2Movie.Extension;
diff --git a/src/BizHawk.Client.Common/movie/bk2/Bk2Movie.cs b/src/BizHawk.Client.Common/movie/bk2/Bk2Movie.cs
index 9dc75a90f8..72ac0ad08a 100644
--- a/src/BizHawk.Client.Common/movie/bk2/Bk2Movie.cs
+++ b/src/BizHawk.Client.Common/movie/bk2/Bk2Movie.cs
@@ -8,9 +8,14 @@ namespace BizHawk.Client.Common
 	{
 		private Bk2Controller _adapter;
 
-		internal Bk2Movie(string filename = null)
+		internal Bk2Movie(string filename)
 		{
-			Filename = filename ?? string.Empty;
+			if (string.IsNullOrWhiteSpace(filename))
+			{
+				throw new ArgumentNullException($"{nameof(filename)} can not be null.");
+			}
+
+			Filename = filename;
 			Header[HeaderKeys.MovieVersion] = "BizHawk v2.0.0";
 		}
 
diff --git a/src/BizHawk.Client.Common/movie/conversions/MovieConversionExtensions.cs b/src/BizHawk.Client.Common/movie/conversions/MovieConversionExtensions.cs
index e000a3a5bb..e800ee7294 100644
--- a/src/BizHawk.Client.Common/movie/conversions/MovieConversionExtensions.cs
+++ b/src/BizHawk.Client.Common/movie/conversions/MovieConversionExtensions.cs
@@ -230,7 +230,7 @@ namespace BizHawk.Client.Common.MovieConversionExtensions
 				}
 			}
 
-			var tas = new TasMovie(newFilename, true) { SaveRam = saveRam };
+			var tas = new TasMovie(newFilename) { SaveRam = saveRam };
 			tas.TasStateManager.Clear();
 			tas.LagLog.Clear();
 
diff --git a/src/BizHawk.Client.Common/movie/tasproj/TasMovie.cs b/src/BizHawk.Client.Common/movie/tasproj/TasMovie.cs
index 8ad5afcc6a..f64bc583fa 100644
--- a/src/BizHawk.Client.Common/movie/tasproj/TasMovie.cs
+++ b/src/BizHawk.Client.Common/movie/tasproj/TasMovie.cs
@@ -13,7 +13,7 @@ namespace BizHawk.Client.Common
 		public new const string Extension = "tasproj";
 
 		/// <exception cref="InvalidOperationException">loaded core does not implement <see cref="IStatable"/></exception>
-		internal TasMovie(string path = null, bool startsFromSavestate = false) : base(path)
+		internal TasMovie(string path, bool startsFromSavestate = false) : base(path)
 		{
 			if (!Global.Emulator.HasSavestates())
 			{
diff --git a/src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.cs b/src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.cs
index 97ce3595c5..c9abcd1715 100644
--- a/src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.cs
+++ b/src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.cs
@@ -623,8 +623,7 @@ namespace BizHawk.Client.EmuHawk
 				return false;
 			}
 
-			var newMovie = MovieService.CreateTas(startsFromSavestate: startsFromSavestate);
-			newMovie.Filename = file.FullName;
+			var newMovie = MovieService.CreateTas(file.FullName, startsFromSavestate);
 			newMovie.BindMarkersToInput = Settings.BindMarkersToInput;
 			newMovie.TasStateManager.InvalidateCallback = GreenzoneInvalidated;
 			
@@ -678,9 +677,10 @@ namespace BizHawk.Client.EmuHawk
 				return;
 			}
 
-			var tasMovie = MovieService.CreateTas();
+			var filename = DefaultTasProjName(); // TODO don't do this, take over any mainform actions that can crash without a filename
+			var tasMovie = MovieService.CreateTas(filename);
 			tasMovie.BindMarkersToInput = Settings.BindMarkersToInput;
-			tasMovie.Filename = DefaultTasProjName(); // TODO don't do this, take over any mainform actions that can crash without a filename
+			
 
 			tasMovie.TasStateManager.InvalidateCallback = GreenzoneInvalidated;
 			tasMovie.PropertyChanged += TasMovie_OnPropertyChanged;