diff --git a/src/Microsoft.AspNetCore.Http.Connections.Common/AvailableTransport.cs b/src/Microsoft.AspNetCore.Http.Connections.Common/AvailableTransport.cs
index 47b1435cae..92d5fe16b4 100644
--- a/src/Microsoft.AspNetCore.Http.Connections.Common/AvailableTransport.cs
+++ b/src/Microsoft.AspNetCore.Http.Connections.Common/AvailableTransport.cs
@@ -8,6 +8,6 @@ namespace Microsoft.AspNetCore.Http.Connections
     public class AvailableTransport
     {
         public string Transport { get; set; }
-        public List<string> TransferFormats { get; set; }
+        public IList<string> TransferFormats { get; set; }
     }
 }
diff --git a/src/Microsoft.AspNetCore.Http.Connections.Common/NegotiationResponse.cs b/src/Microsoft.AspNetCore.Http.Connections.Common/NegotiationResponse.cs
index 2e59277f31..70a930c1a2 100644
--- a/src/Microsoft.AspNetCore.Http.Connections.Common/NegotiationResponse.cs
+++ b/src/Microsoft.AspNetCore.Http.Connections.Common/NegotiationResponse.cs
@@ -8,6 +8,6 @@ namespace Microsoft.AspNetCore.Http.Connections
     public class NegotiationResponse
     {
         public string ConnectionId { get; set; }
-        public List<AvailableTransport> AvailableTransports { get; set; }
+        public IList<AvailableTransport> AvailableTransports { get; set; }
     }
 }
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