diff --git a/log_manager/log_manager.cc b/log_manager/log_manager.cc
index 3e19bcd6b..92eaaff0f 100644
--- a/log_manager/log_manager.cc
+++ b/log_manager/log_manager.cc
@@ -741,13 +741,13 @@ static int logmanager_write_log(
                 timestamp_len = get_timestamp_len();
                 
                 /** Find out how much can be safely written with current block size */
-		if (timestamp_len-1+sesid_str_len-1+str_len > lf->lf_buf_size)
+		if (timestamp_len-1+MAX(sesid_str_len-1,0)+str_len > lf->lf_buf_size)
 		{
 			safe_str_len = lf->lf_buf_size;
 		}
                 else
 		{
-			safe_str_len = timestamp_len-1+sesid_str_len-1+str_len;
+			safe_str_len = timestamp_len-1+MAX(sesid_str_len-1,0)+str_len;
 		}
                 /**
                  * Seek write position and register to block buffer.
@@ -809,10 +809,6 @@ static int logmanager_write_log(
 				 sesid_str_len, 
 				 "[%lu]  ", 
 				 tls_log_info.li_sesid);
-		}
-		
-		if (sesid_str_len != 0)
-		{
 			sesid_str_len -= 1; /*< don't calculate terminating char anymore */
 		}
                 /**