diff --git a/eng/Version.Details.xml b/eng/Version.Details.xml
index 5444590ec8..ab96028e9d 100644
--- a/eng/Version.Details.xml
+++ b/eng/Version.Details.xml
@@ -9,9 +9,9 @@
 -->
 <Dependencies>
   <ProductDependencies>
-    <Dependency Name="Microsoft.AspNetCore.Blazor.Mono" Version="5.0.0-alpha1.19575.1">
+    <Dependency Name="Microsoft.AspNetCore.Blazor.Mono" Version="3.1.0-preview4.19575.3">
       <Uri>https://github.com/aspnet/Blazor</Uri>
-      <Sha>f81c0dbb12a66fb362bf71b3f41833ccf06fc02a</Sha>
+      <Sha>2f17aef68277deb757f5cb48de100bda28648f35</Sha>
     </Dependency>
     <Dependency Name="Microsoft.AspNetCore.Razor.Language" Version="5.0.0-alpha.1.19575.1">
       <Uri>https://github.com/aspnet/AspNetCore-Tooling</Uri>
diff --git a/eng/Versions.props b/eng/Versions.props
index 23df2f6477..1e2489347f 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -94,7 +94,7 @@
     <!-- Only listed explicitly to workaround https://github.com/dotnet/cli/issues/10528 -->
     <MicrosoftNETCorePlatformsPackageVersion>5.0.0-alpha.1.19556.7</MicrosoftNETCorePlatformsPackageVersion>
     <!-- Packages from aspnet/Blazor -->
-    <MicrosoftAspNetCoreBlazorMonoPackageVersion>5.0.0-alpha1.19575.1</MicrosoftAspNetCoreBlazorMonoPackageVersion>
+    <MicrosoftAspNetCoreBlazorMonoPackageVersion>3.1.0-preview4.19575.3</MicrosoftAspNetCoreBlazorMonoPackageVersion>
     <!-- Packages from aspnet/Extensions -->
     <InternalAspNetCoreAnalyzersPackageVersion>5.0.0-alpha1.19563.3</InternalAspNetCoreAnalyzersPackageVersion>
     <MicrosoftAspNetCoreAnalyzerTestingPackageVersion>5.0.0-alpha1.19563.3</MicrosoftAspNetCoreAnalyzerTestingPackageVersion>