diff --git a/packages/rds-signer/src/runtimeConfig.browser.ts b/packages/rds-signer/src/runtimeConfig.browser.ts
index e98cab775200c..66137e89ebc07 100644
--- a/packages/rds-signer/src/runtimeConfig.browser.ts
+++ b/packages/rds-signer/src/runtimeConfig.browser.ts
@@ -1,7 +1,7 @@
 import { Sha256 } from "@aws-crypto/sha256-browser";
 import { invalidProvider } from "@smithy/invalid-dependency";
 
-import { SignerConfig } from "./Signer";
+import type { SignerConfig } from "./Signer";
 
 /**
  * @internal
@@ -9,9 +9,9 @@ import { SignerConfig } from "./Signer";
 export const getRuntimeConfig = (config: SignerConfig) => {
   return {
     runtime: "browser",
-    sha256: config?.sha256 ?? Sha256,
-    credentials: invalidProvider("Credential is missing"),
-    region: invalidProvider("Region is missing"),
     ...config,
+    sha256: config?.sha256 ?? Sha256,
+    credentials: config?.credentials ?? invalidProvider("Credential is missing"),
+    region: config?.region ?? invalidProvider("Region is missing"),
   };
 };
diff --git a/packages/rds-signer/src/runtimeConfig.native.ts b/packages/rds-signer/src/runtimeConfig.native.ts
index e20910ba56558..cb0ec722356cd 100644
--- a/packages/rds-signer/src/runtimeConfig.native.ts
+++ b/packages/rds-signer/src/runtimeConfig.native.ts
@@ -1,7 +1,7 @@
 import { Sha256 } from "@aws-crypto/sha256-js";
 import { invalidProvider } from "@smithy/invalid-dependency";
 
-import { SignerConfig } from "./Signer";
+import type { SignerConfig } from "./Signer";
 
 /**
  * @internal
@@ -9,9 +9,9 @@ import { SignerConfig } from "./Signer";
 export const getRuntimeConfig = (config: SignerConfig) => {
   return {
     runtime: "react-native",
-    sha256: config?.sha256 ?? Sha256,
-    credentials: invalidProvider("Credential is missing"),
-    region: invalidProvider("Region is missing"),
     ...config,
+    sha256: config?.sha256 ?? Sha256,
+    credentials: config?.credentials ?? invalidProvider("Credential is missing"),
+    region: config?.region ?? invalidProvider("Region is missing"),
   };
 };
diff --git a/packages/rds-signer/src/runtimeConfig.ts b/packages/rds-signer/src/runtimeConfig.ts
index 60afbb0ee68a2..d8bf5c667264b 100644
--- a/packages/rds-signer/src/runtimeConfig.ts
+++ b/packages/rds-signer/src/runtimeConfig.ts
@@ -3,7 +3,7 @@ import { NODE_REGION_CONFIG_FILE_OPTIONS, NODE_REGION_CONFIG_OPTIONS } from "@sm
 import { Hash } from "@smithy/hash-node";
 import { loadConfig } from "@smithy/node-config-provider";
 
-import { SignerConfig } from "./Signer";
+import type { SignerConfig } from "./Signer";
 
 /**
  * @internal
@@ -11,6 +11,7 @@ import { SignerConfig } from "./Signer";
 export const getRuntimeConfig = (config: SignerConfig) => {
   return {
     runtime: "node",
+    ...config,
     sha256: config?.sha256 ?? Hash.bind(null, "sha256"),
     credentials:
       config?.credentials ??
@@ -23,6 +24,5 @@ export const getRuntimeConfig = (config: SignerConfig) => {
         ...NODE_REGION_CONFIG_FILE_OPTIONS,
         profile: config.profile,
       }),
-    ...config,
   };
 };