diff --git a/Source/AssetRipper.IO.Files.Tests/FileUtilsTests.cs b/Source/AssetRipper.IO.Files.Tests/FileUtilsTests.cs
new file mode 100644
index 000000000..ae712146c
--- /dev/null
+++ b/Source/AssetRipper.IO.Files.Tests/FileUtilsTests.cs
@@ -0,0 +1,45 @@
+using AssetRipper.IO.Files.Utils;
+
+namespace AssetRipper.IO.Files.Tests;
+
+public static class FileUtilsTests
+{
+	[Test]
+	public static void FilenameTruncationMultibyteCharacter()
+	{
+		Assert.Multiple(() =>
+		{
+			// A        length 3 cont     cont     cont
+			// 01000001 11100110 10010110 10000111 00001010
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文.ext", 4), Is.EqualTo(".ext"));
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文.ext", 5), Is.EqualTo("A.ext"));
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文.ext", 6), Is.EqualTo("A.ext"));
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文.ext", 7), Is.EqualTo("A.ext"));
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文.ext", 8), Is.EqualTo("A文.ext"));
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文.ext", 9), Is.EqualTo("A文.ext"));
+		});
+	}
+	
+	[Test]
+	public static void ExtensionLength()
+	{
+		Assert.Multiple(() =>
+		{
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文.ext", 7), Is.EqualTo("A.ext"));
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文.ext", 8), Is.EqualTo("A文.ext"));
+			
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文.exte", 8), Is.EqualTo("A.exte"));
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文.exte", 9), Is.EqualTo("A文.exte"));
+		});
+	}
+	
+	[Test]
+	public static void WithoutExtension()
+	{
+		Assert.Multiple(() =>
+		{
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文", 3), Is.EqualTo("A"));
+			Assert.That(FileUtils.GetUniqueName("/dir", "A文", 4), Is.EqualTo("A文"));
+		});
+	}
+}
diff --git a/Source/AssetRipper.IO.Files/Utils/FileUtils.cs b/Source/AssetRipper.IO.Files/Utils/FileUtils.cs
index f273fa9f5..ba5452e37 100644
--- a/Source/AssetRipper.IO.Files/Utils/FileUtils.cs
+++ b/Source/AssetRipper.IO.Files/Utils/FileUtils.cs
@@ -1,4 +1,4 @@
-using System.Runtime.InteropServices;
+using System.Text;
 using System.Text.RegularExpressions;
 
 namespace AssetRipper.IO.Files.Utils
@@ -37,12 +37,11 @@ namespace AssetRipper.IO.Files.Utils
 		{
 			string? ext = null;
 			string? name = null;
-			int maxLength = maxNameLength - 4;
 			string validFileName = fileName;
-			if (validFileName.Length > maxLength)
+			if (Encoding.UTF8.GetByteCount(fileName) > maxNameLength)
 			{
 				ext = Path.GetExtension(validFileName);
-				name = validFileName.Substring(0, maxLength - ext.Length);
+				name = TruncateToUTF8ByteLength(fileName, maxNameLength - Encoding.UTF8.GetByteCount(ext));
 				validFileName = name + ext;
 			}
 
@@ -120,5 +119,59 @@ namespace AssetRipper.IO.Files.Utils
 			"lpt1", "lpt2", "lpt3", "lpt4", "lpt5", "lpt6", "lpt7", "lpt8", "lpt9",
 		];
 		private static readonly Regex FileNameRegex = GenerateFileNameRegex();
+
+		private static string TruncateToUTF8ByteLength(string str, int maxLength)
+		{
+			byte[] bytes = Encoding.UTF8.GetBytes(str);
+			int validLength = FindValidByteLength(bytes, maxLength);
+			return Encoding.UTF8.GetString(bytes[..validLength]);
+		}
+
+		private static int FindValidByteLength(byte[] bytes, int maxLength)
+		{
+			int validLength = maxLength;
+
+			// ascii char:      0_
+			// two-byte char:   110_   10_
+			// three-byte char: 1110_  10_ _10_
+			// four-byte char : 11110_ 10_ _10_ _10
+
+			if (maxLength >= bytes.Length)
+			{
+				return bytes.Length;
+			}
+
+			// next byte is a beginning, so we can safely truncate to maxLength
+			byte nextByte = bytes[maxLength];
+			if ((nextByte & 0b11_000000) != 0b10_000000)
+			{
+				return maxLength;
+			}
+
+			// move to end of the last full sequence
+			for (int i = maxLength - 1; i >= 0; i--)
+			{
+				byte currentByte = bytes[i];
+
+				if ((currentByte & 0b11_000000) == 0b10_000000)
+				{
+					// continuation byte
+					validLength--;
+				}
+				else if ((currentByte & 0b10000000) == 0b10000000)
+				{
+					// start of multi-byte sequence
+					validLength--;
+					break;
+				}
+				else
+				{
+					// ascii char
+					break;
+				}
+			}
+
+			return validLength;
+		}
 	}
 }