diff --git a/jest.config.js b/jest.config.js
index dabcda1..c073e0f 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -45,10 +45,10 @@ module.exports = {
   // An object that configures minimum threshold enforcement for coverage results
   coverageThreshold: {
     global: {
-      branches: 91.89,
-      functions: 94.59,
-      lines: 92.42,
-      statements: 92.42,
+      branches: 92.59,
+      functions: 94.73,
+      lines: 92.64,
+      statements: 92.64,
     },
   },
 
diff --git a/src/utils.test.ts b/src/utils.test.ts
index 9aefd4a..62f13db 100644
--- a/src/utils.test.ts
+++ b/src/utils.test.ts
@@ -98,7 +98,7 @@ describe('serializeError', () => {
     const result = serializeError(invalidError7);
     expect(result).toStrictEqual({
       code: rpcCodes.internal,
-      message: getMessageFromCode(rpcCodes.internal),
+      message: invalidError7.message,
       data: {
         cause: {
           code: invalidError7.code,
@@ -209,7 +209,7 @@ describe('serializeError', () => {
     const result = serializeError(error);
     expect(result).toStrictEqual({
       code: errorCodes.rpc.internal,
-      message: getMessageFromCode(errorCodes.rpc.internal),
+      message: error.message,
       data: {
         cause: {
           message: error.message,
@@ -220,7 +220,7 @@ describe('serializeError', () => {
 
     expect(JSON.parse(JSON.stringify(result))).toStrictEqual({
       code: errorCodes.rpc.internal,
-      message: getMessageFromCode(errorCodes.rpc.internal),
+      message: error.message,
       data: {
         cause: {
           message: error.message,
diff --git a/src/utils.ts b/src/utils.ts
index de3e061..6e6bb95 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -145,16 +145,37 @@ function buildError(
     return error;
   }
 
+  const originalMessage = getOriginalMessage(error);
+
   // If the error does not match the JsonRpcError type, use the fallback error, but try to include the original error as `cause`.
   const cause = serializeCause(error);
   const fallbackWithCause = {
     ...fallbackError,
+    ...(originalMessage && { message: originalMessage }),
     data: { cause },
   };
 
   return fallbackWithCause;
 }
 
+/**
+ * Attempts to extract the original `message` property from an error value of uncertain shape.
+ *
+ * @param error - The error in question.
+ * @returns The original message, if it exists and is a non-empty string.
+ */
+function getOriginalMessage(error: unknown): string | undefined {
+  if (
+    isObject(error) &&
+    hasProperty(error, 'message') &&
+    typeof error.message === 'string' &&
+    error.message.length > 0
+  ) {
+    return error.message;
+  }
+  return undefined;
+}
+
 /**
  * Check if the given code is a valid JSON-RPC server error code.
  *