diff --git a/Refit/ApiResponse.cs b/Refit/ApiResponse.cs
index 63f05765a..daa6e803b 100644
--- a/Refit/ApiResponse.cs
+++ b/Refit/ApiResponse.cs
@@ -56,6 +56,7 @@ public ApiResponse(HttpResponseMessage response, T? content, RefitSettings setti
         
 #if NET5_0_OR_GREATER
         [MemberNotNullWhen(true, nameof(Content))]
+        [MemberNotNullWhen(true, nameof(ContentHeaders))]
         [MemberNotNullWhen(false, nameof(Error))]
 #endif
         public bool IsSuccessStatusCode => response.IsSuccessStatusCode;