diff --git a/AwsCryptographyPrimitives/runtimes/net/Crypto.csproj b/AwsCryptographyPrimitives/runtimes/net/Crypto.csproj
index b8d47fc34..d3fd385af 100644
--- a/AwsCryptographyPrimitives/runtimes/net/Crypto.csproj
+++ b/AwsCryptographyPrimitives/runtimes/net/Crypto.csproj
@@ -66,7 +66,7 @@
       System.Collections.Immutable can be removed once dafny.msbuild is updated with
       https://github.com/dafny-lang/dafny.msbuild/pull/10 and versioned
     -->
-    <PackageReference Include="System.Collections.Immutable" Version="1.7.0" />
+    <PackageReference Include="System.Collections.Immutable" Version="9.0.2" />
     <!-- Work around for dafny-lang/dafny/issues/1951; remove once resolved -->
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />
 
diff --git a/AwsCryptographyPrimitives/runtimes/net/tests/Test-Crypto.csproj b/AwsCryptographyPrimitives/runtimes/net/tests/Test-Crypto.csproj
index bf7d59dc9..97d616d4d 100644
--- a/AwsCryptographyPrimitives/runtimes/net/tests/Test-Crypto.csproj
+++ b/AwsCryptographyPrimitives/runtimes/net/tests/Test-Crypto.csproj
@@ -15,7 +15,7 @@
       System.Collections.Immutable can be removed once dafny.msbuild is updated with
       https://github.com/dafny-lang/dafny.msbuild/pull/10 and versioned
     -->
-    <PackageReference Include="System.Collections.Immutable" Version="1.7.0" />
+    <PackageReference Include="System.Collections.Immutable" Version="9.0.2" />
     <!-- Work around for dafny-lang/dafny/issues/1951; remove once resolved -->
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />
   </ItemGroup>
diff --git a/StandardLibrary/runtimes/net/STD.csproj b/StandardLibrary/runtimes/net/STD.csproj
index f101a1d03..2cff75622 100644
--- a/StandardLibrary/runtimes/net/STD.csproj
+++ b/StandardLibrary/runtimes/net/STD.csproj
@@ -61,7 +61,7 @@
       System.Collections.Immutable can be removed once dafny.msbuild is updated with
       https://github.com/dafny-lang/dafny.msbuild/pull/10 and versioned
     -->
-    <PackageReference Include="System.Collections.Immutable" Version="1.7.0" />
+    <PackageReference Include="System.Collections.Immutable" Version="9.0.2" />
     <!-- Work around for dafny-lang/dafny/issues/1951; remove once resolved -->
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />