diff --git a/src/OpenTelemetry.Instrumentation.AspNetCore/Implementation/HttpInMetricsListener.cs b/src/OpenTelemetry.Instrumentation.AspNetCore/Implementation/HttpInMetricsListener.cs
index 52699a12a4..cd9ec3c7ba 100644
--- a/src/OpenTelemetry.Instrumentation.AspNetCore/Implementation/HttpInMetricsListener.cs
+++ b/src/OpenTelemetry.Instrumentation.AspNetCore/Implementation/HttpInMetricsListener.cs
@@ -110,6 +110,9 @@ public override void OnEventWritten(string name, object payload)
                     }
                 }
 
+                // We are relying here on ASP.NET Core to set duration before writing the stop event.
+                // https://github.com/dotnet/aspnetcore/blob/d6fa351048617ae1c8b47493ba1abbe94c3a24cf/src/Hosting/Hosting/src/Internal/HostingApplicationDiagnostics.cs#L449
+                // TODO: Follow up with .NET team if we can continue to rely on this behavior.
                 this.httpServerDuration.Record(Activity.Current.Duration.TotalMilliseconds, tags);
             }
         }
diff --git a/src/OpenTelemetry.Instrumentation.Http/Implementation/HttpHandlerMetricsDiagnosticListener.cs b/src/OpenTelemetry.Instrumentation.Http/Implementation/HttpHandlerMetricsDiagnosticListener.cs
index 124e4351d0..d8306a8436 100644
--- a/src/OpenTelemetry.Instrumentation.Http/Implementation/HttpHandlerMetricsDiagnosticListener.cs
+++ b/src/OpenTelemetry.Instrumentation.Http/Implementation/HttpHandlerMetricsDiagnosticListener.cs
@@ -62,6 +62,9 @@ public override void OnEventWritten(string name, object payload)
                         tags.Add(new KeyValuePair<string, object>(SemanticConventions.AttributeNetPeerPort, request.RequestUri.Port));
                     }
 
+                    // We are relying here on HttpClient library to set duration before writing the stop event.
+                    // https://github.com/dotnet/runtime/blob/90603686d314147017c8bbe1fa8965776ce607d0/src/libraries/System.Net.Http/src/System/Net/Http/DiagnosticsHandler.cs#L178
+                    // TODO: Follow up with .NET team if we can continue to rely on this behavior.
                     this.httpClientDuration.Record(activity.Duration.TotalMilliseconds, tags);
                 }
             }