diff --git a/Directory.Build.targets b/Directory.Build.targets
new file mode 100644
index 00000000..44e5751c
--- /dev/null
+++ b/Directory.Build.targets
@@ -0,0 +1,31 @@
+<Project>
+<UsingTask TaskName="Base64Decode" TaskFactory="RoslynCodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.Core.dll">
+  <ParameterGroup>
+    <EncodedString ParameterType="System.String" Required="true" />
+    <DecodedString Output="true" ParameterType="System.String" />
+  </ParameterGroup>
+  <Task>
+    <Using Namespace="System" />
+    <Using Namespace="System.Text" />
+    <Code Type="Fragment" Language="cs">
+    <![CDATA[
+      DecodedString = Encoding.UTF8.GetString(Convert.FromBase64String(EncodedString));
+    ]]>
+    </Code>
+  </Task>
+</UsingTask>
+
+<!-- This is the decode end of the base64-encoding that gets the release notes into `dotnet pack`.
+     The problem is that we can't supply MsBuild properties that contain MsBuild metacharacters.
+     (At least, I don't know how.)
+     The release notes are liable to contain MsBuild property metacharacters, such as the comma;
+     so just before we `dotnet pack`, we base64-encode it. -->
+<Target Name="DecodeReleaseNotes" BeforeTargets="GenerateNuspec">
+  <Base64Decode EncodedString="$(RELEASE_NOTES)">
+    <Output TaskParameter="DecodedString" PropertyName="DecodedReleaseNotes" />
+  </Base64Decode>
+  <PropertyGroup>
+    <PackageReleaseNotes>$(DecodedReleaseNotes)</PackageReleaseNotes>
+  </PropertyGroup>
+</Target>
+</Project>
diff --git a/build.fsx b/build.fsx
index a5acf001..a2d4b700 100644
--- a/build.fsx
+++ b/build.fsx
@@ -337,13 +337,23 @@ Target.create "RunTests" (fun _ ->
 // --------------------------------------------------------------------------------------
 // Build a NuGet package
 
+let base64 (s : string) =
+    Convert.ToBase64String (Encoding.UTF8.GetBytes s)
+
 type HavePacked = HavePacked
 let packNuGet (_ : HaveTested) : HavePacked =
     Console.Write "Performing dotnet pack... "
     let releaseNotes =
         releaseNotes.Notes
         |> String.concat "\n"
-    runProcess "dotnet" ["pack" ; "--configuration" ; "Release" ; $"-p:Version=%s{buildVersion}" ; "--output" ; "bin" ; $"-p:PackageReleaseNotes=%s{releaseNotes}"]
+        // MsBuild will interpret some characters, apparently including the comma.
+        // To work around this, we pass it in base64-encoded, and pick it up on the other side.
+        |> base64
+    let env = ["RELEASE_NOTES", releaseNotes ; "BUILD_VERSION", buildVersion ] |> Map.ofList
+    if RuntimeInformation.IsOSPlatform OSPlatform.Windows then
+        runProcessWithEnv env "cmd" ["/c" ; "dotnet pack --configuration Release -p:Version=%BUILD_VERSION% --output bin -p:RELEASE_NOTES=%RELEASE_NOTES%"]
+    else
+        runProcessWithEnv env "sh" ["-c" ; "dotnet pack --configuration Release -p:Version=\"$BUILD_VERSION\" --output bin -p:RELEASE_NOTES=\"$RELEASE_NOTES\""]
 
     // I *believe* it is impossible to have a fixed (not floating) version number from a source reference
     // via `dotnet pack`. Without this next bit, FsCheck.Xunit vA.B.C depends on >= FsCheck vA.B.C, not
@@ -401,7 +411,7 @@ let pushNuGet (_ : HaveTested) (_ : HavePacked) =
         if RuntimeInformation.IsOSPlatform OSPlatform.Windows then
             runProcessWithEnv env "cmd" ["/c" ; $"dotnet nuget push %s{package} --api-key %%NUGET_KEY%% --source https://api.nuget.org/v3/index.json"]
         else
-            runProcessWithEnv env "sh" ["-c" ; $"dotnet nuget push %s{package} --api-key $NUGET_KEY --source https://api.nuget.org/v3/index.json"]
+            runProcessWithEnv env "sh" ["-c" ; $"dotnet nuget push %s{package} --api-key \"$NUGET_KEY\" --source https://api.nuget.org/v3/index.json"]
     Console.WriteLine "done."
     HavePushed