diff --git a/src/core/common/logging.cpp b/src/core/common/logging.cpp
index a582726fe..ec0fe0406 100644
--- a/src/core/common/logging.cpp
+++ b/src/core/common/logging.cpp
@@ -96,9 +96,7 @@ static void Log(otLogLevel  aLogLevel,
             break;
         }
 
-#if OPENTHREAD_CONFIG_LOG_PREPEND_REGION
-        IgnoreError(logString.Append("[%s]", levelStr));
-#endif
+        IgnoreError(logString.Append("%s", levelStr));
     }
 #endif // OPENTHREAD_CONFIG_LOG_PREPEND_LEVEL