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 a43a069fd2..68d084f569 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
@@ -41,6 +41,7 @@ import org.jclouds.io.Payloads;
 import org.jclouds.io.payloads.PhantomPayload;
 
 import com.google.common.base.Throwables;
+import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Maps;
 
 /**
@@ -69,7 +70,8 @@ public class BlobBuilderImpl implements BlobBuilder {
 
    @Override
    public BlobBuilder userMetadata(Map<String, String> userMetadata) {
-      this.userMetadata = Maps.newLinkedHashMap(checkNotNull(userMetadata, "userMetadata"));
+      if (userMetadata == null)
+         this.userMetadata = ImmutableMap.copyOf(userMetadata);
       return this;
    }