diff --git a/src/HexManiac.Core/Models/PokemonModel.cs b/src/HexManiac.Core/Models/PokemonModel.cs
index 05dfb866..e5e5fe07 100644
--- a/src/HexManiac.Core/Models/PokemonModel.cs
+++ b/src/HexManiac.Core/Models/PokemonModel.cs
@@ -1391,7 +1391,7 @@ namespace HavenSoft.HexManiac.Core.Models {
       }
 
       public override void ObserveAnchorWritten(ModelDelta changeToken, string anchorName, IFormattedRun run) {
-         Debug.Assert(run.Length > 0); // writing an anchor of length zero is stupid.
+         Debug.Assert(run.Length > 0, $"Trying to write a run of length zero! {run.FormatString} at {run.Start:X6}"); // writing an anchor of length zero is stupid.
          lock (threadlock) {
             int location = run.Start;
             var index = BinarySearch(location);
diff --git a/src/HexManiac.Core/Models/Runs/Factory/LzSpriteRunContentStrategy.cs b/src/HexManiac.Core/Models/Runs/Factory/LzSpriteRunContentStrategy.cs
index 1e381668..d1255ebe 100644
--- a/src/HexManiac.Core/Models/Runs/Factory/LzSpriteRunContentStrategy.cs
+++ b/src/HexManiac.Core/Models/Runs/Factory/LzSpriteRunContentStrategy.cs
@@ -44,7 +44,7 @@ namespace HavenSoft.HexManiac.Core.Models.Runs.Factory {
          }
       }
       public override ErrorInfo TryParseData(IDataModel model, string name, int dataIndex, ref IFormattedRun run) {
-         var error = SpriteRunContentStrategy.IsValid(spriteFormat.BitsPerPixel);
+         var error = SpriteRunContentStrategy.IsValid(spriteFormat);
          if (error.HasError) return error;
          run = new LzSpriteRun(spriteFormat, model, dataIndex, run.PointerSources);
          if (run.Length == LZRun.DecompressedTooLong) return new ErrorInfo("Decompressed more bytes than expected. Add a ! to override this.");
diff --git a/src/HexManiac.Core/Models/Runs/Factory/LzTilemapRunContentStrategy.cs b/src/HexManiac.Core/Models/Runs/Factory/LzTilemapRunContentStrategy.cs
index a8270fd3..5c0b2401 100644
--- a/src/HexManiac.Core/Models/Runs/Factory/LzTilemapRunContentStrategy.cs
+++ b/src/HexManiac.Core/Models/Runs/Factory/LzTilemapRunContentStrategy.cs
@@ -22,7 +22,7 @@ namespace HavenSoft.HexManiac.Core.Models.Runs.Factory {
       }
 
       public override ErrorInfo TryParseData(IDataModel model, string name, int dataIndex, ref IFormattedRun run) {
-         var error = SpriteRunContentStrategy.IsValid(TilemapFormat.BitsPerPixel);
+         var error = SpriteRunContentStrategy.IsValid(TilemapFormat);
          if (error.HasError) return error;
          var lzRun = new LZRun(model, dataIndex);
          var rowRemainder = lzRun.DecompressedLength % TilemapFormat.TileWidth;
diff --git a/src/HexManiac.Core/Models/Runs/Factory/LzTilesetRunContentStrategy.cs b/src/HexManiac.Core/Models/Runs/Factory/LzTilesetRunContentStrategy.cs
index 87affcdc..ed50738f 100644
--- a/src/HexManiac.Core/Models/Runs/Factory/LzTilesetRunContentStrategy.cs
+++ b/src/HexManiac.Core/Models/Runs/Factory/LzTilesetRunContentStrategy.cs
@@ -23,7 +23,7 @@ namespace HavenSoft.HexManiac.Core.Models.Runs.Factory {
       }
 
       public override ErrorInfo TryParseData(IDataModel model, string name, int dataIndex, ref IFormattedRun run) {
-         var error = SpriteRunContentStrategy.IsValid(TilesetFormat.BitsPerPixel);
+         var error = SpriteRunContentStrategy.IsValid(TilesetFormat);
          if (error.HasError) return error;
          var lzRun = new LzTilesetRun(TilesetFormat, model, dataIndex);
          if (lzRun.Length == LZRun.DecompressedTooLong) return new ErrorInfo("Decompressed more bytes than expected. Add a ! to override this.");
diff --git a/src/HexManiac.Core/Models/Runs/Factory/SpriteRunContentStrategy.cs b/src/HexManiac.Core/Models/Runs/Factory/SpriteRunContentStrategy.cs
index ccb07705..5b445e4f 100644
--- a/src/HexManiac.Core/Models/Runs/Factory/SpriteRunContentStrategy.cs
+++ b/src/HexManiac.Core/Models/Runs/Factory/SpriteRunContentStrategy.cs
@@ -36,17 +36,37 @@ namespace HavenSoft.HexManiac.Core.Models.Runs.Factory {
          }
       }
       public override ErrorInfo TryParseData(IDataModel model, string name, int dataIndex, ref IFormattedRun run) {
-         var error = IsValid(spriteFormat.BitsPerPixel);
+         var error = IsValid(spriteFormat);
          if (error.HasError) return error;
          run = new SpriteRun(model, dataIndex, spriteFormat, run.PointerSources);
          return ErrorInfo.NoError;
       }
 
-      public static ErrorInfo IsValid(int bitsPerPixel) {
-         if (!new[] { 1, 2, 4, 8 }.Contains(bitsPerPixel)) {
+      public static ErrorInfo IsValid(TilemapFormat format) {
+         if (!format.BitsPerPixel.IsAny(1, 2, 4, 8)) {
             return new ErrorInfo("Sprite bpp must be 1, 2, 4, or 8.");
          }
          return ErrorInfo.NoError;
       }
+
+      public static ErrorInfo IsValid(TilesetFormat format) {
+         if (!format.BitsPerPixel.IsAny(1, 2, 4, 8)) {
+            return new ErrorInfo("Sprite bpp must be 1, 2, 4, or 8.");
+         }
+         if (format.MaxTiles == 0 || format.Tiles == 0) {
+            return new ErrorInfo("Tilesets must have at least 1 tile.");
+         }
+         return ErrorInfo.NoError;
+      }
+
+      public static ErrorInfo IsValid(SpriteFormat format) {
+         if (!format.BitsPerPixel.IsAny(1, 2, 4, 8)) {
+            return new ErrorInfo("Sprite bpp must be 1, 2, 4, or 8.");
+         }
+         if (format.ExpectedByteLength <= 0) {
+            return new ErrorInfo("Sprite width/height must positive.");
+         }
+         return ErrorInfo.NoError;
+      }
    }
 }
diff --git a/src/HexManiac.Core/Models/Runs/Factory/TilemapRunContentStrategy.cs b/src/HexManiac.Core/Models/Runs/Factory/TilemapRunContentStrategy.cs
index a00ad297..15113314 100644
--- a/src/HexManiac.Core/Models/Runs/Factory/TilemapRunContentStrategy.cs
+++ b/src/HexManiac.Core/Models/Runs/Factory/TilemapRunContentStrategy.cs
@@ -28,7 +28,7 @@ namespace HavenSoft.HexManiac.Core.Models.Runs.Factory {
       }
 
       public override ErrorInfo TryParseData(IDataModel model, string name, int dataIndex, ref IFormattedRun run) {
-         var error = SpriteRunContentStrategy.IsValid(format.BitsPerPixel);
+         var error = SpriteRunContentStrategy.IsValid(format);
          if (error.HasError) return error;
          var newRun = new TilemapRun(model, dataIndex, format);
          run = newRun;
diff --git a/src/HexManiac.Core/Models/Runs/Factory/TilesetRunContentStrategy.cs b/src/HexManiac.Core/Models/Runs/Factory/TilesetRunContentStrategy.cs
index 393e0b55..688ea675 100644
--- a/src/HexManiac.Core/Models/Runs/Factory/TilesetRunContentStrategy.cs
+++ b/src/HexManiac.Core/Models/Runs/Factory/TilesetRunContentStrategy.cs
@@ -31,7 +31,7 @@ namespace HavenSoft.HexManiac.Core.Models.Runs.Factory {
       }
 
       public override ErrorInfo TryParseData(IDataModel model, string name, int dataIndex, ref IFormattedRun run) {
-         var error = SpriteRunContentStrategy.IsValid(TilesetFormat.BitsPerPixel);
+         var error = SpriteRunContentStrategy.IsValid(TilesetFormat);
          if (error.HasError) return error;
          var newRun = new TilesetRun(TilesetFormat, model, run.Start, run.PointerSources);
          var nextRun = model.GetNextRun(run.Start + 1);
diff --git a/src/HexManiac.Tests/ImageTests.cs b/src/HexManiac.Tests/ImageTests.cs
index 805a892a..9f7b2026 100644
--- a/src/HexManiac.Tests/ImageTests.cs
+++ b/src/HexManiac.Tests/ImageTests.cs
@@ -882,6 +882,19 @@ namespace HavenSoft.HexManiac.Tests {
          Assert.Equal("Decompressed more bytes than expected. Add a ! to override this.", Errors[0]);
       }
 
+      [Theory]
+      [InlineData("`ucs4x0x1`")]
+      [InlineData("`ucs4x1x0`")]
+      [InlineData("`uct4x0`")]
+      [InlineData("`lzs4x0x1`")]
+      [InlineData("`lzs4x1x0`")]
+      [InlineData("`lzt4x0`")]
+      public void ImageFormatWithZeroDimensionErrors(string format) {
+         WriteCompressedData(0, 0x20);
+         ViewPort.Edit($"^image{format} ");
+         Assert.Single(Errors);
+      }
+
       private void WriteCompressedData(int start, int length) {
          var compressedData = LZRun.Compress(new byte[length], 0, length);
          for (int i = 0; i < compressedData.Count; i++) Model[start + i] = compressedData[i];