Code style: Replace tab with space.
diff --git a/include/ndn-cpp/security/identity/private-key-storage.hpp b/include/ndn-cpp/security/identity/private-key-storage.hpp
index 5ade942..d253aa3 100644
--- a/include/ndn-cpp/security/identity/private-key-storage.hpp
+++ b/include/ndn-cpp/security/identity/private-key-storage.hpp
@@ -7,7 +7,7 @@
  */
 
 #ifndef NDN_PRIVATE_KEY_STORAGE_HPP
-#define	NDN_PRIVATE_KEY_STORAGE_HPP
+#define NDN_PRIVATE_KEY_STORAGE_HPP
 
 #include <string>
 #include "../../util/blob.hpp"