diff --git a/src/blobstore/interface/Blob.h b/src/blobstore/interface/Blob.h
index fc8c5803..caaa8317 100644
--- a/src/blobstore/interface/Blob.h
+++ b/src/blobstore/interface/Blob.h
@@ -2,6 +2,8 @@
 #ifndef BLOBSTORE_INTERFACE_BLOB_H_
 #define BLOBSTORE_INTERFACE_BLOB_H_
 
+#include <cstring>
+
 namespace blobstore {
 
 class Blob {
@@ -10,6 +12,8 @@ public:
 
   virtual void *data() = 0;
   virtual const void *data() const = 0;
+
+  virtual size_t size() const = 0;
 };
 
 }
diff --git a/src/blobstore/interface/BlobStore.h b/src/blobstore/interface/BlobStore.h
index 95269f29..213a413f 100644
--- a/src/blobstore/interface/BlobStore.h
+++ b/src/blobstore/interface/BlobStore.h
@@ -14,7 +14,7 @@ class BlobStore {
 public:
   virtual ~BlobStore() {}
 
-  virtual std::unique_ptr<Blob> create(const std::string &key) = 0;
+  virtual std::unique_ptr<Blob> create(const std::string &key, size_t size) = 0;
   virtual std::unique_ptr<Blob> load(const std::string &key) = 0;
   //TODO Needed for performance? Or is deleting loaded blobs enough?
   //virtual void remove(const std::string &key) = 0;