diff --git a/blobstore/src/main/java/org/jclouds/blobstore/domain/internal/BlobBuilderImpl.java b/blobstore/src/main/java/org/jclouds/blobstore/domain/internal/BlobBuilderImpl.java
index f43e03ceab..e6d94e1c78 100644
--- a/blobstore/src/main/java/org/jclouds/blobstore/domain/internal/BlobBuilderImpl.java
+++ b/blobstore/src/main/java/org/jclouds/blobstore/domain/internal/BlobBuilderImpl.java
@@ -181,7 +181,7 @@ public class BlobBuilderImpl implements BlobBuilder {
 
       @Override
       public PayloadBlobBuilder contentLength(long contentLength) {
-         checkArgument(contentLength >= 0, "content length must be non-negative");
+         checkArgument(contentLength >= 0, "content length must be non-negative, was: %s", contentLength);
          payload.getContentMetadata().setContentLength(contentLength);
          return this;
       }