diff --git a/Tharga.Toolkit.Standard/Tharga.Toolkit.Standard.csproj b/Tharga.Toolkit.Standard/Tharga.Toolkit.Standard.csproj
index 2cb5bd3..11ead32 100644
--- a/Tharga.Toolkit.Standard/Tharga.Toolkit.Standard.csproj
+++ b/Tharga.Toolkit.Standard/Tharga.Toolkit.Standard.csproj
@@ -15,6 +15,10 @@
     <PackageProjectUrl>https://github.com/Tharga/Toolkit</PackageProjectUrl>
     <PackageReadmeFile>README.md</PackageReadmeFile>
     <IncludeSymbols>true</IncludeSymbols>
+    <!-- Without this, pack emits the legacy .symbols.nupkg, whose name still ends
+         in .nupkg, so the release push loop uploads it as a regular package and
+         nuget.org rejects it as a duplicate. No symbols ever shipped. -->
+    <SymbolPackageFormat>snupkg</SymbolPackageFormat>
     <IncludeSource>true</IncludeSource>
     <PublishRepositoryUrl>true</PublishRepositoryUrl>
     <EmbedUntrackedSources>true</EmbedUntrackedSources>
diff --git a/Tharga.Toolkit/Tharga.Toolkit.csproj b/Tharga.Toolkit/Tharga.Toolkit.csproj
index c0f0f53..c1c640b 100644
--- a/Tharga.Toolkit/Tharga.Toolkit.csproj
+++ b/Tharga.Toolkit/Tharga.Toolkit.csproj
@@ -15,6 +15,10 @@
 		<PackageProjectUrl>https://github.com/Tharga/Toolkit</PackageProjectUrl>
 		<PackageReadmeFile>README.md</PackageReadmeFile>
 		<IncludeSymbols>true</IncludeSymbols>
+		<!-- Without this, pack emits the legacy .symbols.nupkg, whose name still ends
+		     in .nupkg, so the release push loop uploads it as a regular package and
+		     nuget.org rejects it as a duplicate. No symbols ever shipped. -->
+		<SymbolPackageFormat>snupkg</SymbolPackageFormat>
 		<IncludeSource>true</IncludeSource>
 		<PublishRepositoryUrl>true</PublishRepositoryUrl>
 		<EmbedUntrackedSources>true</EmbedUntrackedSources>