diff --git a/packages/grpc-js-core/src/metadata.ts b/packages/grpc-js-core/src/metadata.ts
index de41f02f..71fe5e09 100644
--- a/packages/grpc-js-core/src/metadata.ts
+++ b/packages/grpc-js-core/src/metadata.ts
@@ -43,7 +43,7 @@ function normalizeKey(key: string): string {
 
 function validate(key: string, value?: MetadataValue): void {
   if (!isLegalKey(key)) {
-    throw new Error('Metadata key"' + key + '" contains illegal characters');
+    throw new Error('Metadata key "' + key + '" contains illegal characters');
   }
   if (value != null) {
     if (isBinaryKey(key)) {
diff --git a/packages/grpc-js-core/test/test-metadata.ts b/packages/grpc-js-core/test/test-metadata.ts
index dd2d7c94..4dff735d 100644
--- a/packages/grpc-js-core/test/test-metadata.ts
+++ b/packages/grpc-js-core/test/test-metadata.ts
@@ -52,7 +52,7 @@ describe('Metadata', () => {
       });
       assert.throws(() => {
         metadata.set('key$', 'value');
-      });
+      }, /Error: Metadata key "key\$" contains illegal characters/);
       assert.throws(() => {
         metadata.set('', 'value');
       });