diff --git a/core/src/backend/storage.rs b/core/src/backend/storage.rs
index 5b2b316c9..356eab6a8 100644
--- a/core/src/backend/storage.rs
+++ b/core/src/backend/storage.rs
@@ -15,7 +15,7 @@ pub trait StorageBackend: Downcast {
 impl_downcast!(StorageBackend);
 
 pub struct MemoryStorageBackend {
-    pub map: HashMap<String, String>,
+    map: HashMap<String, String>,
 }
 
 impl Default for MemoryStorageBackend {