diff --git a/src/libraries/System.Text.Encodings.Web/ref/System.Text.Encodings.Web.csproj b/src/libraries/System.Text.Encodings.Web/ref/System.Text.Encodings.Web.csproj
index 24b4be39e3164..a255727581606 100644
--- a/src/libraries/System.Text.Encodings.Web/ref/System.Text.Encodings.Web.csproj
+++ b/src/libraries/System.Text.Encodings.Web/ref/System.Text.Encodings.Web.csproj
@@ -3,6 +3,7 @@
     <TargetFrameworks>$(NetCoreAppCurrent);netstandard2.0;net461</TargetFrameworks>
     <ExcludeCurrentNetCoreAppFromPackage>true</ExcludeCurrentNetCoreAppFromPackage>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <AssemblyVersion Condition="!$(TargetFramework.StartsWith('net4'))">5.0.0.0</AssemblyVersion>
     <!-- Only CLS-compliant members can be abstract -->
     <NoWarn>$(NoWarn);CS3011</NoWarn>
     <Nullable>enable</Nullable>
@@ -20,4 +21,4 @@
     <PackageReference Include="System.Buffers" Version="$(SystemBuffersVersion)" />
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
   </ItemGroup>
-</Project>
\ No newline at end of file
+</Project>