diff --git a/src/Avalonia.Dialogs/ByteSizeHelper.cs b/src/Avalonia.Dialogs/ByteSizeHelper.cs
index a3769ed169..d849e33399 100644
--- a/src/Avalonia.Dialogs/ByteSizeHelper.cs
+++ b/src/Avalonia.Dialogs/ByteSizeHelper.cs
@@ -1,25 +1,40 @@
+using System;
+
 namespace Avalonia.Dialogs
 {
     internal static class ByteSizeHelper
     {
+        private const string formatTemplate = "{0}{1:0.#} {2}";
+
         private static readonly string[] Prefixes =
         {
             "B",
             "KB",
             "MB",
             "GB",
-            "TB"
+            "TB",
+            "PB",
+            "EB",
+            "ZB",
+            "YB" 
         };
 
-        public static string ToString(long bytes)
+        public static string ToString(ulong bytes)
         {
-            var index = 0;
-            while (bytes >= 1000)
+            if (bytes == 0)
             {
-                bytes /= 1000;
-                ++index;
+                return string.Format(formatTemplate, null, 0, Prefixes[0]);
             }
-            return $"{bytes:N} {Prefixes[index]}";
+
+            var absSize = Math.Abs((double)bytes);
+            var fpPower = Math.Log(absSize, 1000);
+            var intPower = (int)fpPower;
+            var iUnit = intPower >= Prefixes.Length
+                ? Prefixes.Length - 1
+                : intPower;
+            var normSize = absSize / Math.Pow(1000, iUnit);
+
+            return string.Format(formatTemplate,bytes < 0 ? "-" : null, normSize, Prefixes[iUnit]);
         }
     }
 }
diff --git a/src/Avalonia.Dialogs/FileSizeStringConverter.cs b/src/Avalonia.Dialogs/FileSizeStringConverter.cs
index f5b399dc7a..5b41b9da35 100644
--- a/src/Avalonia.Dialogs/FileSizeStringConverter.cs
+++ b/src/Avalonia.Dialogs/FileSizeStringConverter.cs
@@ -12,7 +12,7 @@ namespace Avalonia.Dialogs
         {
             if (value is long size && size > 0)
             {
-                return ByteSizeHelper.ToString(size);
+                return ByteSizeHelper.ToString((ulong)size);
             }
 
             return "";
diff --git a/src/Avalonia.Dialogs/ManagedFileChooserSources.cs b/src/Avalonia.Dialogs/ManagedFileChooserSources.cs
index 83ee2fef69..7bce866fde 100644
--- a/src/Avalonia.Dialogs/ManagedFileChooserSources.cs
+++ b/src/Avalonia.Dialogs/ManagedFileChooserSources.cs
@@ -36,9 +36,6 @@ namespace Avalonia.Dialogs
             Environment.SpecialFolder.MyVideos
         };
 
-        private static string[] s_sizeSuffixes = { "B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };
-        private const string formatTemplate = "{0}{1:0.#} {2}";
-
         public static ManagedFileChooserNavigationItem[] DefaultGetUserDirectories()
         {
             return s_folders.Select(Environment.GetFolderPath).Distinct()
@@ -51,29 +48,6 @@ namespace Avalonia.Dialogs
                 }).ToArray();
         }
 
-        public static event EventHandler SourcesChanged;
-
-        private static string ByteToHumanReadableUnits(ulong size)
-        {
-
-            if (size == 0)
-            {
-                return string.Format(formatTemplate, null, 0, s_sizeSuffixes[0]);
-            }
-
-            var absSize = Math.Abs((double)size);
-            var fpPower = Math.Log(absSize, 1000);
-            var intPower = (int)fpPower;
-            var iUnit = intPower >= s_sizeSuffixes.Length
-                ? s_sizeSuffixes.Length - 1
-                : intPower;
-            var normSize = absSize / Math.Pow(1000, iUnit);
-
-            return string.Format(
-                formatTemplate,
-                size < 0 ? "-" : null, normSize, s_sizeSuffixes[iUnit]);
-        }
-
         public static ManagedFileChooserNavigationItem[] DefaultGetFileSystemRoots()
         {
             if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
@@ -119,7 +93,7 @@ namespace Avalonia.Dialogs
                                return new ManagedFileChooserNavigationItem
                                {
 
-                                   DisplayName = dNameEmpty ? $"{ByteToHumanReadableUnits(x.DriveSizeBytes)} Volume"
+                                   DisplayName = dNameEmpty ? $"{ByteSizeHelper.ToString(x.DriveSizeBytes)} Volume"
                                                             : x.DriveLabel,
                                    Path = x.MountPath
                                };