diff --git a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.browser.ts.template b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.browser.ts.template
index 43ba05ed972..fab8b334c58 100644
--- a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.browser.ts.template
+++ b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.browser.ts.template
@@ -4,7 +4,7 @@ import { getRuntimeConfig as getSharedRuntimeConfig } from "./runtimeConfig.shar
 /**
  * @internal
  */
-export const getRuntimeConfig = (config: ${clientConfigName}) => {
+export const getRuntimeConfig = (config: ${clientConfigName} = {}) => {
   const clientSharedValues = getSharedRuntimeConfig(config);
   return {
     ...clientSharedValues,
diff --git a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.native.ts.template b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.native.ts.template
index 705735d7203..117f122384d 100644
--- a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.native.ts.template
+++ b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.native.ts.template
@@ -4,7 +4,7 @@ import { getRuntimeConfig as getBrowserRuntimeConfig } from "./runtimeConfig.bro
 /**
  * @internal
  */
-export const getRuntimeConfig = (config: ${clientConfigName}) => {
+export const getRuntimeConfig = (config: ${clientConfigName} = {}) => {
   const browserDefaults = getBrowserRuntimeConfig(config);
   return {
     ...browserDefaults,
diff --git a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.shared.ts.template b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.shared.ts.template
index 5ec08befe15..67141d8c19c 100644
--- a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.shared.ts.template
+++ b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.shared.ts.template
@@ -3,7 +3,7 @@ import { ${clientConfigName} } from "${clientModuleName}";
 /**
  * @internal
  */
-export const getRuntimeConfig = (config: ${clientConfigName}) => ({
+export const getRuntimeConfig = (config: ${clientConfigName} = {}) => ({
   apiVersion: "${apiVersion}",
 ${customizations}
 });
diff --git a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.ts.template b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.ts.template
index 532d4ca44a3..30034a8b99b 100644
--- a/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.ts.template
+++ b/smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/runtimeConfig.ts.template
@@ -4,7 +4,7 @@ import { getRuntimeConfig as getSharedRuntimeConfig } from "./runtimeConfig.shar
 /**
  * @internal
  */
-export const getRuntimeConfig = (config: ${clientConfigName}) => {
+export const getRuntimeConfig = (config: ${clientConfigName} = {}) => {
   const clientSharedValues = getSharedRuntimeConfig(config);
   return {
     ...clientSharedValues,