diff --git a/cosmo/Cosmo.csproj b/cosmo/Cosmo.csproj
index 40478b8..71295b7 100644
--- a/cosmo/Cosmo.csproj
+++ b/cosmo/Cosmo.csproj
@@ -7,6 +7,6 @@
     <Copyright>Copyright © Joshua Kempner 2008-2022</Copyright>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="reactiveui" Version="18.4.34" />
+    <PackageReference Include="reactiveui" Version="19.4.1" />
   </ItemGroup>
 </Project>
\ No newline at end of file