diff --git a/src/IdentityServer/Services/Default/ServerSideSessionRefreshTokenService.cs b/src/IdentityServer/Services/Default/ServerSideSessionRefreshTokenService.cs
index 2ca5c5937..775ee730c 100644
--- a/src/IdentityServer/Services/Default/ServerSideSessionRefreshTokenService.cs
+++ b/src/IdentityServer/Services/Default/ServerSideSessionRefreshTokenService.cs
@@ -43,7 +43,7 @@ public ServerSideSessionRefreshTokenService(
 
 
     /// <inheritdoc/>
-    public async Task<TokenValidationResult> ValidateRefreshTokenAsync(string tokenHandle, Client client)
+    public virtual async Task<TokenValidationResult> ValidateRefreshTokenAsync(string tokenHandle, Client client)
     {
         var result = await Inner.ValidateRefreshTokenAsync(tokenHandle, client);