diff --git a/DiscordChatExporter.Core/DiscordChatExporter.Core.csproj b/DiscordChatExporter.Core/DiscordChatExporter.Core.csproj
index ea27afc..aa7adc1 100644
--- a/DiscordChatExporter.Core/DiscordChatExporter.Core.csproj
+++ b/DiscordChatExporter.Core/DiscordChatExporter.Core.csproj
@@ -16,7 +16,6 @@
     </ItemGroup>
 
     <ItemGroup>
-        <PackageReference Include="ByteSize" Version="1.3.0" />
         <PackageReference Include="Failsafe" Version="1.1.0" />
         <PackageReference Include="Newtonsoft.Json" Version="12.0.1" />
         <PackageReference Include="Onova" Version="2.4.2" />
diff --git a/DiscordChatExporter.Core/Models/Attachment.cs b/DiscordChatExporter.Core/Models/Attachment.cs
index a92c235..4e54314 100644
--- a/DiscordChatExporter.Core/Models/Attachment.cs
+++ b/DiscordChatExporter.Core/Models/Attachment.cs
@@ -1,5 +1,4 @@
 using System;
-using ByteSizeLib;
 
 namespace DiscordChatExporter.Core.Models
 {
@@ -23,9 +22,9 @@ namespace DiscordChatExporter.Core.Models
                                FileName.EndsWith(".gif", StringComparison.OrdinalIgnoreCase) ||
                                FileName.EndsWith(".bmp", StringComparison.OrdinalIgnoreCase);
 
-        public ByteSize FileSize { get; }
+        public FileSize FileSize { get; }
 
-        public Attachment(string id, int? width, int? height, string url, string fileName, ByteSize fileSize)
+        public Attachment(string id, int? width, int? height, string url, string fileName, FileSize fileSize)
         {
             Id = id;
             Url = url;
diff --git a/DiscordChatExporter.Core/Models/FileSize.cs b/DiscordChatExporter.Core/Models/FileSize.cs
new file mode 100644
index 0000000..d52464b
--- /dev/null
+++ b/DiscordChatExporter.Core/Models/FileSize.cs
@@ -0,0 +1,84 @@
+using System;
+
+namespace DiscordChatExporter.Core.Models
+{
+    // Loosely based on https://github.com/omar/ByteSize (MIT license)
+
+    public struct FileSize
+    {
+        public const long BytesInKiloByte = 1024;
+        public const long BytesInMegaByte = 1024 * BytesInKiloByte;
+        public const long BytesInGigaByte = 1024 * BytesInMegaByte;
+        public const long BytesInTeraByte = 1024 * BytesInGigaByte;
+        public const long BytesInPetaByte = 1024 * BytesInTeraByte;
+
+        public const string ByteSymbol = "B";
+        public const string KiloByteSymbol = "KB";
+        public const string MegaByteSymbol = "MB";
+        public const string GigaByteSymbol = "GB";
+        public const string TeraByteSymbol = "TB";
+        public const string PetaByteSymbol = "PB";
+
+        public double Bytes { get; }
+        public double KiloBytes => Bytes / BytesInKiloByte;
+        public double MegaBytes => Bytes / BytesInMegaByte;
+        public double GigaBytes => Bytes / BytesInGigaByte;
+        public double TeraBytes => Bytes / BytesInTeraByte;
+        public double PetaBytes => Bytes / BytesInPetaByte;
+
+        public string LargestWholeNumberSymbol
+        {
+            get
+            {
+                // Absolute value is used to deal with negative values
+                if (Math.Abs(PetaBytes) >= 1)
+                    return PetaByteSymbol;
+
+                if (Math.Abs(TeraBytes) >= 1)
+                    return TeraByteSymbol;
+
+                if (Math.Abs(GigaBytes) >= 1)
+                    return GigaByteSymbol;
+
+                if (Math.Abs(MegaBytes) >= 1)
+                    return MegaByteSymbol;
+
+                if (Math.Abs(KiloBytes) >= 1)
+                    return KiloByteSymbol;
+
+                return ByteSymbol;
+            }
+        }
+
+        public double LargestWholeNumberValue
+        {
+            get
+            {
+                // Absolute value is used to deal with negative values
+                if (Math.Abs(PetaBytes) >= 1)
+                    return PetaBytes;
+
+                if (Math.Abs(TeraBytes) >= 1)
+                    return TeraBytes;
+
+                if (Math.Abs(GigaBytes) >= 1)
+                    return GigaBytes;
+
+                if (Math.Abs(MegaBytes) >= 1)
+                    return MegaBytes;
+
+                if (Math.Abs(KiloBytes) >= 1)
+                    return KiloBytes;
+
+                return Bytes;
+            }
+        }
+
+        public FileSize(double bytes)
+        {
+            Bytes = bytes;
+        }
+
+        public override string ToString() => $"{LargestWholeNumberValue:0.##} {LargestWholeNumberSymbol}";
+    }
+}
\ No newline at end of file
diff --git a/DiscordChatExporter.Core/Services/DataService.Parsers.cs b/DiscordChatExporter.Core/Services/DataService.Parsers.cs
index 837548c..426831e 100644
--- a/DiscordChatExporter.Core/Services/DataService.Parsers.cs
+++ b/DiscordChatExporter.Core/Services/DataService.Parsers.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Drawing;
 using System.Linq;
-using ByteSizeLib;
 using DiscordChatExporter.Core.Internal;
 using DiscordChatExporter.Core.Models;
 using Newtonsoft.Json.Linq;
@@ -72,7 +71,7 @@ namespace DiscordChatExporter.Core.Services
             var fileName = json["filename"].Value<string>();
             var fileSizeBytes = json["size"].Value<long>();
 
-            var fileSize = ByteSize.FromBytes(fileSizeBytes);
+            var fileSize = new FileSize(fileSizeBytes);
 
             return new Attachment(id, width, height, url, fileName, fileSize);
         }
diff --git a/Readme.md b/Readme.md
index 647f071..6a396e4 100644
--- a/Readme.md
+++ b/Readme.md
@@ -34,7 +34,6 @@ DiscordChatExporter can be used to export message history from a [Discord](https
 - [Scriban](https://github.com/lunet-io/scriban)
 - [CommandLineParser](https://github.com/commandlineparser/commandline)
 - [Ookii.Dialogs](https://github.com/caioproiete/ookii-dialogs-wpf)
-- [ByteSize](https://github.com/omar/ByteSize)
 - [Failsafe](https://github.com/Tyrrrz/Failsafe)
 - [Gress](https://github.com/Tyrrrz/Gress)
 - [Onova](https://github.com/Tyrrrz/Onova)