Code style: Replace tab with space.
diff --git a/include/ndn-cpp/security/security-common.hpp b/include/ndn-cpp/security/security-common.hpp
index 1222480..76fc849 100644
--- a/include/ndn-cpp/security/security-common.hpp
+++ b/include/ndn-cpp/security/security-common.hpp
@@ -6,7 +6,7 @@
  */
 
 #ifndef NDN_SECURITY_COMMON_HPP
-#define	NDN_SECURITY_COMMON_HPP
+#define NDN_SECURITY_COMMON_HPP
 
 namespace ndn {