diff --git a/GeneGenie.Gedcom/GeneGenie.Gedcom.csproj b/GeneGenie.Gedcom/GeneGenie.Gedcom.csproj
index d7311f4..703eb3a 100644
--- a/GeneGenie.Gedcom/GeneGenie.Gedcom.csproj
+++ b/GeneGenie.Gedcom/GeneGenie.Gedcom.csproj
@@ -25,7 +25,7 @@
 
     <ItemGroup>
         <PackageReference Include="System.Collections.Immutable" Version="9.0.0" />
-        <PackageReference Include="System.Collections.Immutable" Version="8.0.0" />
+        <PackageReference Include="System.Collections.Immutable" Version="9.0.0" />
     </ItemGroup>
 
     <PropertyGroup>