diff --git a/drivers/syslog/ramlog.c b/drivers/syslog/ramlog.c
index 6a2a85bb2e..5776ee6af3 100644
--- a/drivers/syslog/ramlog.c
+++ b/drivers/syslog/ramlog.c
@@ -257,9 +257,10 @@ static void ramlog_initbuf(void)
     {
       cur = priv->rl_buffer[i];
 
-      if (!isascii(cur))
+      if (!isprint(cur) && !isspace(cur) && cur != '\0')
         {
           memset(priv->rl_buffer, 0, priv->rl_bufsize);
+          is_empty = true;
           break;
         }
       else if (prev && !cur)
diff --git a/drivers/syslog/syslog_rpmsg.c b/drivers/syslog/syslog_rpmsg.c
index 49873263e0..0409797ffa 100644
--- a/drivers/syslog/syslog_rpmsg.c
+++ b/drivers/syslog/syslog_rpmsg.c
@@ -418,9 +418,10 @@ void syslog_rpmsg_init_early(FAR void *buffer, size_t size)
     {
       cur = priv->buffer[i];
 
-      if (!isascii(cur))
+      if (!isprint(cur) && !isspace(cur) && cur != '\0')
         {
-          memset(priv->buffer, 0, size);
+          memset(buffer, 0, size);
+          is_empty = true;
           break;
         }
       else if (prev && !cur)