diff --git a/sdk/src/Core/Amazon.Runtime/Pipeline/Handlers/Marshaller.cs b/sdk/src/Core/Amazon.Runtime/Pipeline/Handlers/Marshaller.cs
index 6ead057028a8..3b7fc0315665 100644
--- a/sdk/src/Core/Amazon.Runtime/Pipeline/Handlers/Marshaller.cs
+++ b/sdk/src/Core/Amazon.Runtime/Pipeline/Handlers/Marshaller.cs
@@ -115,9 +115,7 @@ private static void SetUserAgentHeader(IRequestContext requestContext)
             if (!string.IsNullOrEmpty(clientAppId))
                 sb.Append(" app/").Append(InternalSDKUtils.ReplaceInvalidUserAgentCharacters(clientAppId));
 
-            var retryMode = ToUserAgentHeaderString(requestContext.ClientConfig.RetryMode);
-            Debug.Assert(retryMode != requestContext.ClientConfig.RetryMode.ToString().ToLower(), "Invalid RetryMode string.");
-            sb.Append(" cfg/retry-mode#}").Append(retryMode);
+            sb.Append(" cfg/retry-mode#}").Append(ToUserAgentHeaderString(requestContext.ClientConfig.RetryMode));
 
             sb.Append(" md/").Append(requestContext.IsAsync ? "ClientAsync" : "ClientSync");
 
@@ -143,10 +141,15 @@ private static void SetUserAgentHeader(IRequestContext requestContext)
 
         private static string ToUserAgentHeaderString(RequestRetryMode requestRetryMode)
         {
-            if (requestRetryMode == RequestRetryMode.Adaptive)
-                return "adaptive";
-            else
-                return "standard";
+            switch (requestRetryMode)
+            {
+                case RequestRetryMode.Standard:
+                    return "standard";
+                case RequestRetryMode.Adaptive:
+                    return "adaptive";
+                default:
+                    return requestRetryMode.ToString().ToLowerInvariant();
+            }
         }
     }
 }
diff --git a/sdk/test/Services/SecurityToken/UnitTests/Custom/StaticCheckTests.cs b/sdk/test/Services/SecurityToken/UnitTests/Custom/StaticCheckTests.cs
index 1f516a944cfd..1b576b6ae127 100644
--- a/sdk/test/Services/SecurityToken/UnitTests/Custom/StaticCheckTests.cs
+++ b/sdk/test/Services/SecurityToken/UnitTests/Custom/StaticCheckTests.cs
@@ -83,5 +83,15 @@ public void EnsureCredentialProfileDetectorSetup()
             // the properties are used at least once.
             Assert.IsTrue(profileOptionsProperties.SetEquals(referencedProfileOptionsProperties));
         }
+
+        [TestMethod]
+        public void LookForRequestRetryModeChanges()
+        {
+            var expectedHash = "2FC699DB6A4284C5D53F3B7FA4E64165576FD1F6AE458BC737AE503F06DFBE4C";
+            AssertExtensions.AssertEnumUnchanged(
+                typeof(RequestRetryMode),
+                expectedHash,
+                "The Amazon.Runtime.Internal.Marshaller.ToUserAgentHeaderString method implementation may need to be updated.");
+        }
     }
 }
\ No newline at end of file