diff --git a/aws-runtime/aws-http/api/aws-http.api b/aws-runtime/aws-http/api/aws-http.api
index b716520c2a4..88a9dfd857f 100644
--- a/aws-runtime/aws-http/api/aws-http.api
+++ b/aws-runtime/aws-http/api/aws-http.api
@@ -103,6 +103,12 @@ public final class aws/sdk/kotlin/runtime/http/OsMetadata {
 	public fun toString ()Ljava/lang/String;
 }
 
+public final class aws/sdk/kotlin/runtime/http/S3ExpressHttpSigner : aws/smithy/kotlin/runtime/http/auth/HttpSigner {
+	public fun <init> (Laws/smithy/kotlin/runtime/http/auth/AwsHttpSigner;)V
+	public final fun getAwsHttpSigner ()Laws/smithy/kotlin/runtime/http/auth/AwsHttpSigner;
+	public fun sign (Laws/smithy/kotlin/runtime/http/auth/SignHttpRequest;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
+}
+
 public final class aws/sdk/kotlin/runtime/http/SdkMetadata {
 	public fun <init> (Ljava/lang/String;Ljava/lang/String;)V
 	public final fun component1 ()Ljava/lang/String;
@@ -162,8 +168,11 @@ public final class aws/sdk/kotlin/runtime/http/interceptors/AwsSpanInterceptor :
 	public fun readBeforeTransmit (Laws/smithy/kotlin/runtime/client/ProtocolRequestInterceptorContext;)V
 }
 
-public final class aws/sdk/kotlin/runtime/http/interceptors/UnsupportedSigningAlgorithmInterceptor : aws/smithy/kotlin/runtime/client/Interceptor {
+public final class aws/sdk/kotlin/runtime/http/interceptors/S3ExpressCrc32ChecksumInterceptor : aws/smithy/kotlin/runtime/client/Interceptor {
 	public fun <init> ()V
+	public fun <init> (Ljava/lang/String;)V
+	public synthetic fun <init> (Ljava/lang/String;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public final fun getChecksumAlgorithmHeaderName ()Ljava/lang/String;
 	public fun modifyBeforeAttemptCompletion-gIAlu-s (Laws/smithy/kotlin/runtime/client/ResponseInterceptorContext;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun modifyBeforeCompletion-gIAlu-s (Laws/smithy/kotlin/runtime/client/ResponseInterceptorContext;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun modifyBeforeDeserialization (Laws/smithy/kotlin/runtime/client/ProtocolResponseInterceptorContext;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@@ -185,53 +194,8 @@ public final class aws/sdk/kotlin/runtime/http/interceptors/UnsupportedSigningAl
 	public fun readBeforeTransmit (Laws/smithy/kotlin/runtime/client/ProtocolRequestInterceptorContext;)V
 }
 
-public final class aws/sdk/kotlin/runtime/http/middleware/AwsRetryHeaderMiddleware : aws/smithy/kotlin/runtime/http/operation/MutateMiddleware {
-	public fun <init> ()V
-	public fun handle (Laws/smithy/kotlin/runtime/http/operation/OperationRequest;Laws/smithy/kotlin/runtime/io/Handler;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-	public synthetic fun handle (Ljava/lang/Object;Laws/smithy/kotlin/runtime/io/Handler;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-	public fun install (Laws/smithy/kotlin/runtime/http/operation/SdkHttpOperation;)V
-}
-
-public final class aws/sdk/kotlin/runtime/http/middleware/RecursionDetection : aws/smithy/kotlin/runtime/http/operation/ModifyRequestMiddleware {
-	public fun <init> ()V
-	public fun <init> (Laws/smithy/kotlin/runtime/util/EnvironmentProvider;)V
-	public synthetic fun <init> (Laws/smithy/kotlin/runtime/util/EnvironmentProvider;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
-	public fun install (Laws/smithy/kotlin/runtime/http/operation/SdkHttpOperation;)V
-	public fun modifyRequest (Laws/smithy/kotlin/runtime/http/operation/OperationRequest;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-	public synthetic fun modifyRequest (Ljava/lang/Object;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-}
-
-public final class aws/sdk/kotlin/runtime/http/middleware/UserAgent : aws/smithy/kotlin/runtime/http/operation/ModifyRequestMiddleware {
-	public fun <init> (Laws/sdk/kotlin/runtime/http/AwsUserAgentMetadata;)V
-	public fun install (Laws/smithy/kotlin/runtime/http/operation/SdkHttpOperation;)V
-	public fun modifyRequest (Laws/smithy/kotlin/runtime/http/operation/OperationRequest;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-	public synthetic fun modifyRequest (Ljava/lang/Object;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-}
-
-public final class aws/sdk/kotlin/runtime/http/operation/ConfigMetadata : aws/sdk/kotlin/runtime/http/operation/TypedUserAgentMetadata {
-	public fun <init> (Ljava/lang/String;Ljava/lang/String;)V
-	public final fun component1 ()Ljava/lang/String;
-	public final fun component2 ()Ljava/lang/String;
-	public final fun copy (Ljava/lang/String;Ljava/lang/String;)Laws/sdk/kotlin/runtime/http/operation/ConfigMetadata;
-	public static synthetic fun copy$default (Laws/sdk/kotlin/runtime/http/operation/ConfigMetadata;Ljava/lang/String;Ljava/lang/String;ILjava/lang/Object;)Laws/sdk/kotlin/runtime/http/operation/ConfigMetadata;
-	public fun equals (Ljava/lang/Object;)Z
-	public final fun getName ()Ljava/lang/String;
-	public final fun getValue ()Ljava/lang/String;
-	public fun hashCode ()I
-	public fun toString ()Ljava/lang/String;
-}
-
-public final class aws/sdk/kotlin/runtime/http/S3ExpressHttpSigner : aws/smithy/kotlin/runtime/http/auth/HttpSigner {
-	public fun <init> (Laws/smithy/kotlin/runtime/http/auth/AwsHttpSigner;)V
-	public final fun getAwsHttpSigner ()Laws/smithy/kotlin/runtime/http/auth/AwsHttpSigner;
-	public fun sign (Laws/smithy/kotlin/runtime/http/auth/SignHttpRequest;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
-}
-
-public final class aws/sdk/kotlin/runtime/http/interceptors/S3ExpressCrc32ChecksumInterceptor : aws/smithy/kotlin/runtime/client/Interceptor {
+public final class aws/sdk/kotlin/runtime/http/interceptors/S3ExpressDisableChecksumInterceptor : aws/smithy/kotlin/runtime/client/Interceptor {
 	public fun <init> ()V
-	public fun <init> (Ljava/lang/String;)V
-	public synthetic fun <init> (Ljava/lang/String;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
-	public final fun getChecksumAlgorithmHeaderName ()Ljava/lang/String;
 	public fun modifyBeforeAttemptCompletion-gIAlu-s (Laws/smithy/kotlin/runtime/client/ResponseInterceptorContext;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun modifyBeforeCompletion-gIAlu-s (Laws/smithy/kotlin/runtime/client/ResponseInterceptorContext;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun modifyBeforeDeserialization (Laws/smithy/kotlin/runtime/client/ProtocolResponseInterceptorContext;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@@ -253,7 +217,7 @@ public final class aws/sdk/kotlin/runtime/http/interceptors/S3ExpressCrc32Checks
 	public fun readBeforeTransmit (Laws/smithy/kotlin/runtime/client/ProtocolRequestInterceptorContext;)V
 }
 
-public final class aws/sdk/kotlin/runtime/http/interceptors/S3ExpressDisableChecksumInterceptor : aws/smithy/kotlin/runtime/client/Interceptor {
+public final class aws/sdk/kotlin/runtime/http/interceptors/UnsupportedSigningAlgorithmInterceptor : aws/smithy/kotlin/runtime/client/Interceptor {
 	public fun <init> ()V
 	public fun modifyBeforeAttemptCompletion-gIAlu-s (Laws/smithy/kotlin/runtime/client/ResponseInterceptorContext;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public fun modifyBeforeCompletion-gIAlu-s (Laws/smithy/kotlin/runtime/client/ResponseInterceptorContext;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@@ -276,6 +240,42 @@ public final class aws/sdk/kotlin/runtime/http/interceptors/S3ExpressDisableChec
 	public fun readBeforeTransmit (Laws/smithy/kotlin/runtime/client/ProtocolRequestInterceptorContext;)V
 }
 
+public final class aws/sdk/kotlin/runtime/http/middleware/AwsRetryHeaderMiddleware : aws/smithy/kotlin/runtime/http/operation/MutateMiddleware {
+	public fun <init> ()V
+	public fun handle (Laws/smithy/kotlin/runtime/http/operation/OperationRequest;Laws/smithy/kotlin/runtime/io/Handler;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
+	public synthetic fun handle (Ljava/lang/Object;Laws/smithy/kotlin/runtime/io/Handler;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
+	public fun install (Laws/smithy/kotlin/runtime/http/operation/SdkHttpOperation;)V
+}
+
+public final class aws/sdk/kotlin/runtime/http/middleware/RecursionDetection : aws/smithy/kotlin/runtime/http/operation/ModifyRequestMiddleware {
+	public fun <init> ()V
+	public fun <init> (Laws/smithy/kotlin/runtime/util/EnvironmentProvider;)V
+	public synthetic fun <init> (Laws/smithy/kotlin/runtime/util/EnvironmentProvider;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public fun install (Laws/smithy/kotlin/runtime/http/operation/SdkHttpOperation;)V
+	public fun modifyRequest (Laws/smithy/kotlin/runtime/http/operation/OperationRequest;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
+	public synthetic fun modifyRequest (Ljava/lang/Object;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
+}
+
+public final class aws/sdk/kotlin/runtime/http/middleware/UserAgent : aws/smithy/kotlin/runtime/http/operation/ModifyRequestMiddleware {
+	public fun <init> (Laws/sdk/kotlin/runtime/http/AwsUserAgentMetadata;)V
+	public fun install (Laws/smithy/kotlin/runtime/http/operation/SdkHttpOperation;)V
+	public fun modifyRequest (Laws/smithy/kotlin/runtime/http/operation/OperationRequest;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
+	public synthetic fun modifyRequest (Ljava/lang/Object;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
+}
+
+public final class aws/sdk/kotlin/runtime/http/operation/ConfigMetadata : aws/sdk/kotlin/runtime/http/operation/TypedUserAgentMetadata {
+	public fun <init> (Ljava/lang/String;Ljava/lang/String;)V
+	public final fun component1 ()Ljava/lang/String;
+	public final fun component2 ()Ljava/lang/String;
+	public final fun copy (Ljava/lang/String;Ljava/lang/String;)Laws/sdk/kotlin/runtime/http/operation/ConfigMetadata;
+	public static synthetic fun copy$default (Laws/sdk/kotlin/runtime/http/operation/ConfigMetadata;Ljava/lang/String;Ljava/lang/String;ILjava/lang/Object;)Laws/sdk/kotlin/runtime/http/operation/ConfigMetadata;
+	public fun equals (Ljava/lang/Object;)Z
+	public final fun getName ()Ljava/lang/String;
+	public final fun getValue ()Ljava/lang/String;
+	public fun hashCode ()I
+	public fun toString ()Ljava/lang/String;
+}
+
 public final class aws/sdk/kotlin/runtime/http/operation/CustomUserAgentMetadata {
 	public fun <init> ()V
 	public fun <init> (Ljava/util/Map;Ljava/util/List;)V
diff --git a/codegen/aws-sdk-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/customization/s3/ClientConfigIntegration.kt b/codegen/aws-sdk-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/customization/s3/ClientConfigIntegration.kt
index 7f829b7ec63..8b9b0334118 100644
--- a/codegen/aws-sdk-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/customization/s3/ClientConfigIntegration.kt
+++ b/codegen/aws-sdk-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/customization/s3/ClientConfigIntegration.kt
@@ -90,8 +90,6 @@ class ClientConfigIntegration : KotlinIntegration {
                 },
             )
 
-            // FIXME Figure out why the default value is not being used properly.
-//            propertyType = ConfigPropertyType.RequiredWithDefault("S3ExpressCredentialsProvider(this.credentialsProvider)")
             propertyType = ConfigPropertyType.Custom(
                 render = { _, writer ->
                     writer.write("public val $name: S3ExpressCredentialsProvider = builder.$name ?: SdkS3ExpressCredentialsProvider(this.credentialsProvider)")
diff --git a/codegen/aws-sdk-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/customization/s3/express/SigV4S3ExpressAuthSchemeIntegration.kt b/codegen/aws-sdk-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/customization/s3/express/SigV4S3ExpressAuthSchemeIntegration.kt
index 7d42a9d70ca..d91ba06e626 100644
--- a/codegen/aws-sdk-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/customization/s3/express/SigV4S3ExpressAuthSchemeIntegration.kt
+++ b/codegen/aws-sdk-codegen/src/main/kotlin/aws/sdk/kotlin/codegen/customization/s3/express/SigV4S3ExpressAuthSchemeIntegration.kt
@@ -27,7 +27,6 @@ import software.amazon.smithy.kotlin.codegen.rendering.protocol.*
 import software.amazon.smithy.kotlin.codegen.utils.getOrNull
 import software.amazon.smithy.model.Model
 import software.amazon.smithy.model.node.Node
-import software.amazon.smithy.model.node.ObjectNode
 import software.amazon.smithy.model.shapes.OperationShape
 import software.amazon.smithy.model.shapes.ServiceShape
 import software.amazon.smithy.model.shapes.ShapeId
@@ -93,19 +92,13 @@ open class SigV4S3ExpressAuthSchemeHandler : AuthSchemeHandler {
     }
 }
 
-private fun String.toAuthOptionFactoryFn(): Symbol? =
-    when (this) {
-        "sigv4-s3express" -> AwsRuntimeTypes.Config.Auth.sigV4S3Express
-        else -> null
-    }
-
 private fun renderAuthSchemes(writer: KotlinWriter, authSchemes: Expression, expressionRenderer: ExpressionRenderer) {
     writer.writeInline("#T to ", RuntimeTypes.SmithyClient.Endpoints.SigningContextAttributeKey)
     writer.withBlock("listOf(", ")") {
         authSchemes.toNode().expectArrayNode().forEach {
             val scheme = it.expectObjectNode()
             val schemeName = scheme.expectStringMember("name").value
-            val authFactoryFn = schemeName.toAuthOptionFactoryFn() ?: return@forEach
+            val authFactoryFn = if (schemeName == "sigv4-s3express") AwsRuntimeTypes.Config.Auth.sigV4S3Express else return@forEach
 
             withBlock("#T(", "),", authFactoryFn) {
                 // we delegate back to the expression visitor for each of these fields because it's possible to
@@ -117,9 +110,8 @@ private fun renderAuthSchemes(writer: KotlinWriter, authSchemes: Expression, exp
                 writeInline("disableDoubleUriEncode = ")
                 renderOrElse(expressionRenderer, scheme.getBooleanMember("disableDoubleEncoding"), "false")
 
-                when (schemeName) {
-                    "sigv4-s3express" -> renderSigV4ExpressFields(writer, scheme, expressionRenderer)
-                }
+                writer.writeInline("signingRegion = ")
+                writer.renderOrElse(expressionRenderer, scheme.getStringMember("signingRegion"), "null")
             }
         }
     }
@@ -137,8 +129,3 @@ private fun KotlinWriter.renderOrElse(
     }
     write(",")
 }
-
-private fun renderSigV4ExpressFields(writer: KotlinWriter, scheme: ObjectNode, expressionRenderer: ExpressionRenderer) {
-    writer.writeInline("signingRegion = ")
-    writer.renderOrElse(expressionRenderer, scheme.getStringMember("signingRegion"), "null")
-}