diff --git a/doc/config.but b/doc/config.but
index 488c157e..1990a92a 100644
--- a/doc/config.but
+++ b/doc/config.but
@@ -214,12 +214,15 @@ digits.
 \b \c{&T} will be replaced by the current time, as six digits
 (HHMMSS) with no punctuation.
 
-\b \c{&H} will be replaced by the host name you are connecting to.
+\b \c{&H} will be replaced by the host name you are connecting to
+(or the serial line, for a serial connection).
 
 \b \c{&P} will be replaced by the port number you are connecting to on
 the target host.
 
-For example, if you enter the host name
+(These are all case-insensitive.)
+
+For example, if you enter the file name
 \c{c:\\puttylogs\\log-&h-&y&m&d-&t.dat}, you will end up with files looking
 like
 
diff --git a/logging.c b/logging.c
index 147feb9a..2c3ab3f6 100644
--- a/logging.c
+++ b/logging.c
@@ -22,8 +22,9 @@ struct LogContext {
     int logtype;                       /* cached out of conf */
 };
 
-static Filename *xlatlognam(Filename *s, char *hostname, int port,
-                            struct tm *tm);
+static Filename *xlatlognam(const Filename *s,
+                            const char *hostname, int port,
+                            const struct tm *tm);
 
 /*
  * Internal wrapper function which must be called for _all_ output
@@ -173,7 +174,7 @@ void logfopen(LogContext *ctx)
         filename_free(ctx->currlogfilename);
     ctx->currlogfilename =
         xlatlognam(conf_get_filename(ctx->conf, CONF_logfilename),
-                   conf_get_str(ctx->conf, CONF_host),
+                   conf_dest(ctx->conf),    /* hostname or serial line */
                    conf_get_int(ctx->conf, CONF_port), &tm);
 
     if (open_for_write_would_lose_data(ctx->currlogfilename)) {
@@ -431,10 +432,12 @@ void log_reconfig(LogContext *ctx, Conf *conf)
  *
  * "&Y":YYYY   "&m":MM   "&d":DD   "&T":hhmmss   "&h":<hostname>   "&&":&
  */
-static Filename *xlatlognam(Filename *src, char *hostname, int port,
-                            struct tm *tm)
+static Filename *xlatlognam(const Filename *src,
+                            const char *hostname, int port,
+                            const struct tm *tm)
 {
-    char buf[32], *bufp;
+    char buf[32];
+    const char *bufp;
     int size;
     strbuf *buffer;
     const char *s;