diff --git a/packages/aws-cdk-lib/aws-cloudwatch/lib/metric.ts b/packages/aws-cdk-lib/aws-cloudwatch/lib/metric.ts
index 652f626cb9fbf..38eaf28d7dbc0 100644
--- a/packages/aws-cdk-lib/aws-cloudwatch/lib/metric.ts
+++ b/packages/aws-cdk-lib/aws-cloudwatch/lib/metric.ts
@@ -591,7 +591,7 @@ export class Metric implements IMetric {
 
     dimsArray.map(key => {
       if (dims[key] === undefined || dims[key] === null) {
-        throw new cdk.UnscopedValidationError(`Dimension value of '${dims[key]}' is invalid`);
+        throw new cdk.UnscopedValidationError(`Dimension value of '${dims[key]}' is invalid for key: ${key}`);
       }
       if (key.length < 1 || key.length > 255) {
         throw new cdk.UnscopedValidationError(`Dimension name must be at least 1 and no more than 255 characters; received ${key}`);