diff --git a/src/AcDream.Launcher.Core/Installation/LauncherInstaller.cs b/src/AcDream.Launcher.Core/Installation/LauncherInstaller.cs
index f936aaa3..1307ddab 100644
--- a/src/AcDream.Launcher.Core/Installation/LauncherInstaller.cs
+++ b/src/AcDream.Launcher.Core/Installation/LauncherInstaller.cs
@@ -1,6 +1,7 @@
 using AcDream.Launcher.Core.Integrity;
 using AcDream.Launcher.Core.Launching;
 using AcDream.Platform;
+using System.Globalization;
 
 namespace AcDream.Launcher.Core.Installation;
 
@@ -326,9 +327,9 @@ public sealed class LauncherInstaller : ILauncherInstaller
         {
             string message =
                 $"The optimized world-data rebuild needs at least "
-                + $"{FullRebuildRequiredFreeBytes / (1024d * 1024d * 1024d):N1} GiB free "
+                + $"{FormatGiB(FullRebuildRequiredFreeBytes)} GiB free "
                 + $"beside the active package; only "
-                + $"{availableBytes / (1024d * 1024d * 1024d):N1} GiB is available.";
+                + $"{FormatGiB(availableBytes)} GiB is available.";
             Report(progress, LauncherInstallPhase.Failed, message);
             throw new LauncherInstallException(message);
         }
@@ -636,6 +637,9 @@ public sealed class LauncherInstaller : ILauncherInstaller
             .ConfigureAwait(false);
     }
 
+    private static string FormatGiB(long bytes) =>
+        (bytes / (1024d * 1024d * 1024d)).ToString("N1", CultureInfo.InvariantCulture);
+
     public async Task<LauncherInstallResult> ApplyContentUpdateAsync(
         string datDirectory,
         int threads,
diff --git a/tests/AcDream.Launcher.Core.Tests/Installation/LauncherInstallerTests.cs b/tests/AcDream.Launcher.Core.Tests/Installation/LauncherInstallerTests.cs
index dcd326f9..0ad09778 100644
--- a/tests/AcDream.Launcher.Core.Tests/Installation/LauncherInstallerTests.cs
+++ b/tests/AcDream.Launcher.Core.Tests/Installation/LauncherInstallerTests.cs
@@ -1,4 +1,5 @@
 using System.Diagnostics;
+using System.Globalization;
 using System.Text.Json.Nodes;
 using AcDream.Launcher.Core.Integrity;
 using AcDream.Launcher.Core.Installation;
@@ -150,28 +151,37 @@ public sealed class LauncherInstallerTests : IDisposable
     [Fact]
     public async Task InsufficientFreeSpaceStopsBeforeBakeAndReportsExactRequirement()
     {
-        bool childStarted = false;
-        var runner = new FakeBakeProcessRunner((_, _, _) =>
+        CultureInfo originalCulture = CultureInfo.CurrentCulture;
+        CultureInfo.CurrentCulture = CultureInfo.GetCultureInfo("sv-SE");
+        try
         {
-            childStarted = true;
-            return Task.FromResult(new BakeProcessResult(0, string.Empty));
-        });
-        var installer = new LauncherInstaller(
-            _paths,
-            _bakeExecutable,
-            processRunner: runner,
-            availableFreeSpace: _ =>
-                LauncherInstaller.FullRebuildRequiredFreeBytes - 1);
+            bool childStarted = false;
+            var runner = new FakeBakeProcessRunner((_, _, _) =>
+            {
+                childStarted = true;
+                return Task.FromResult(new BakeProcessResult(0, string.Empty));
+            });
+            var installer = new LauncherInstaller(
+                _paths,
+                _bakeExecutable,
+                processRunner: runner,
+                availableFreeSpace: _ =>
+                    LauncherInstaller.FullRebuildRequiredFreeBytes - 1);
 
-        LauncherInstallException error = await Assert.ThrowsAsync<LauncherInstallException>(
-            () => installer.InstallAsync(_dats, threads: 2));
+            LauncherInstallException error = await Assert.ThrowsAsync<LauncherInstallException>(
+                () => installer.InstallAsync(_dats, threads: 2));
 
-        Assert.False(childStarted);
-        Assert.Contains("2.0 GiB", error.Message, StringComparison.Ordinal);
-        Assert.Contains("active package", error.Message, StringComparison.Ordinal);
-        Assert.False(File.Exists(
-            LauncherInstaller.GetFullRebuildCandidatePath(
-                Path.Combine(_paths.DataDirectory, "pak", "acdream.pak"))));
+            Assert.False(childStarted);
+            Assert.Contains("2.0 GiB", error.Message, StringComparison.Ordinal);
+            Assert.Contains("active package", error.Message, StringComparison.Ordinal);
+            Assert.False(File.Exists(
+                LauncherInstaller.GetFullRebuildCandidatePath(
+                    Path.Combine(_paths.DataDirectory, "pak", "acdream.pak"))));
+        }
+        finally
+        {
+            CultureInfo.CurrentCulture = originalCulture;
+        }
     }
 
     [Fact]