diff --git a/src/Squidex.Domain.Apps.Core.Model/Squidex.Domain.Apps.Core.Model.csproj b/src/Squidex.Domain.Apps.Core.Model/Squidex.Domain.Apps.Core.Model.csproj
index a16027693..452047bfa 100644
--- a/src/Squidex.Domain.Apps.Core.Model/Squidex.Domain.Apps.Core.Model.csproj
+++ b/src/Squidex.Domain.Apps.Core.Model/Squidex.Domain.Apps.Core.Model.csproj
@@ -10,7 +10,7 @@
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     <PackageReference Include="Freezable.Fody" Version="1.9.1" />
-    <PackageReference Include="System.Collections.Immutable" Version="1.5.0" />
+    <PackageReference Include="System.Collections.Immutable" Version="1.4.0" />
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />
   </ItemGroup>
   <ItemGroup>
diff --git a/src/Squidex.Domain.Apps.Core.Operations/Squidex.Domain.Apps.Core.Operations.csproj b/src/Squidex.Domain.Apps.Core.Operations/Squidex.Domain.Apps.Core.Operations.csproj
index 97df564a6..9df26a770 100644
--- a/src/Squidex.Domain.Apps.Core.Operations/Squidex.Domain.Apps.Core.Operations.csproj
+++ b/src/Squidex.Domain.Apps.Core.Operations/Squidex.Domain.Apps.Core.Operations.csproj
@@ -23,7 +23,7 @@
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     <PackageReference Include="RefactoringEssentials" Version="5.6.0" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.0.2" />
-    <PackageReference Include="System.Collections.Immutable" Version="1.5.0" />
+    <PackageReference Include="System.Collections.Immutable" Version="1.4.0" />
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />
     <PackageReference Include="WindowsAzure.Storage" Version="9.3.0" />
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diff --git a/src/Squidex.Domain.Apps.Entities/Squidex.Domain.Apps.Entities.csproj b/src/Squidex.Domain.Apps.Entities/Squidex.Domain.Apps.Entities.csproj
index 9a624c05e..d70c35d48 100644
--- a/src/Squidex.Domain.Apps.Entities/Squidex.Domain.Apps.Entities.csproj
+++ b/src/Squidex.Domain.Apps.Entities/Squidex.Domain.Apps.Entities.csproj
@@ -20,6 +20,7 @@
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     <PackageReference Include="RefactoringEssentials" Version="5.6.0" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.0.2" />
+    <PackageReference Include="System.Collections.Immutable" Version="1.4.0" />
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />
   </ItemGroup>
   <PropertyGroup>
diff --git a/src/Squidex.Infrastructure/Squidex.Infrastructure.csproj b/src/Squidex.Infrastructure/Squidex.Infrastructure.csproj
index da9bf5fd7..068ac6153 100644
--- a/src/Squidex.Infrastructure/Squidex.Infrastructure.csproj
+++ b/src/Squidex.Infrastructure/Squidex.Infrastructure.csproj
@@ -18,7 +18,7 @@
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     <PackageReference Include="SixLabors.ImageSharp" Version="1.0.0-beta0004" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.0.2" />
-    <PackageReference Include="System.Collections.Immutable" Version="1.5.0" />
+    <PackageReference Include="System.Collections.Immutable" Version="1.4.0" />
     <PackageReference Include="System.Linq" Version="4.3.0" />
     <PackageReference Include="System.Reactive" Version="4.0.0" />
     <PackageReference Include="System.Reflection.TypeExtensions" Version="4.5.0" />