diff --git a/include/proto/log.h b/include/proto/log.h
index 72b9f2b39..08a9a1bf6 100644
--- a/include/proto/log.h
+++ b/include/proto/log.h
@@ -70,7 +70,7 @@ void add_to_logformat_list(char *start, char *end, int type, struct list *list_f
  * Variable name are preceded by % and composed by characters [a-zA-Z0-9]* : %varname
  * You can set arguments using { } : %{many arguments}varname
  */
-void parse_logformat_string(const char *str, struct proxy *curproxy, struct list *list_format, int capabilities);
+void parse_logformat_string(const char *str, struct proxy *curproxy, struct list *list_format, int options);
 /*
  * Displays the message on stderr with the date and pid. Overrides the quiet
  * mode during startup.
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 175e30cdc..315e5ed3d 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -6365,10 +6365,10 @@ out_uri_auth_compat:
 		}
 
 		if (curproxy->logformat_string)
-			parse_logformat_string(curproxy->logformat_string, curproxy, &curproxy->logformat, curproxy->mode);
+			parse_logformat_string(curproxy->logformat_string, curproxy, &curproxy->logformat, LOG_OPT_MANDATORY);
 
 		if (curproxy->uniqueid_format_string)
-			parse_logformat_string(curproxy->uniqueid_format_string, curproxy, &curproxy->format_unique_id, PR_MODE_HTTP);
+			parse_logformat_string(curproxy->uniqueid_format_string, curproxy, &curproxy->format_unique_id, 0);
 
 		/* first, we will invert the servers list order */
 		newsrv = NULL;
diff --git a/src/log.c b/src/log.c
index d36d87988..338a98601 100644
--- a/src/log.c
+++ b/src/log.c
@@ -362,9 +362,9 @@ void add_sample_to_logformat_list(char *text, char *arg, int arg_len, struct pro
  *  str: the string to parse
  *  curproxy: the proxy affected
  *  list_format: the destination list
- *  capabilities: PR_MODE_TCP_ | PR_MODE_HTTP
+ *  options: LOG_OPT_* to force on every node
  */
-void parse_logformat_string(const char *fmt, struct proxy *curproxy, struct list *list_format, int capabilities)
+void parse_logformat_string(const char *fmt, struct proxy *curproxy, struct list *list_format, int options)
 {
 	char *sp, *str, *backfmt; /* start pointer for text parts */
 	char *arg = NULL; /* start pointer for args */
@@ -374,7 +374,6 @@ void parse_logformat_string(const char *fmt, struct proxy *curproxy, struct list
 	int cformat; /* current token format */
 	int pformat; /* previous token format */
 	struct logformat_node *tmplf, *back;
-	int options = 0;
 
 	sp = str = backfmt = strdup(fmt);
 	curproxy->to_log |= LW_INIT;
@@ -593,7 +592,7 @@ char *lf_text_len(char *dst, const char *src, size_t len, size_t size, struct lo
 		size--;
 	}
 
-	if (src) {
+	if (src && len) {
 		if (++len > size)
 			len = size;
 		len = strlcpy2(dst, src, len);
@@ -601,6 +600,11 @@ char *lf_text_len(char *dst, const char *src, size_t len, size_t size, struct lo
 		size -= len;
 		dst += len;
 	}
+	else if ((node->options & (LOG_OPT_QUOTE|LOG_OPT_MANDATORY)) == LOG_OPT_MANDATORY) {
+		if (size < 2)
+			return NULL;
+		*(dst++) = '-';
+	}
 
 	if (node->options & LOG_OPT_QUOTE) {
 		if (size < 2)
@@ -908,9 +912,7 @@ int build_logline(struct session *s, char *dst, size_t maxsize, struct list *lis
 					key = sample_fetch_string(be, s, txn, SMP_OPT_DIR_REQ|SMP_OPT_FINAL, tmp->expr);
 				if (!key && (tmp->options & LOG_OPT_RES_CAP))
 					key = sample_fetch_string(be, s, txn, SMP_OPT_DIR_RES|SMP_OPT_FINAL, tmp->expr);
-				if (!key)
-					break;
-				ret = lf_text_len(tmplog, key->data.str.str, key->data.str.len, dst + maxsize - tmplog, tmp);
+				ret = lf_text_len(tmplog, key ? key->data.str.str : NULL, key ? key->data.str.len : 0, dst + maxsize - tmplog, tmp);
 				if (ret == 0)
 					goto out;
 				tmplog = ret;
diff --git a/src/proto_http.c b/src/proto_http.c
index da3935c3e..0040cbfd1 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -8109,7 +8109,7 @@ struct http_req_rule *parse_http_req_cond(const char **args, const char *file, i
 		rule->arg.hdr_add.name = strdup(args[cur_arg]);
 		rule->arg.hdr_add.name_len = strlen(rule->arg.hdr_add.name);
 		LIST_INIT(&rule->arg.hdr_add.fmt);
-		parse_logformat_string(args[cur_arg + 1], proxy, &rule->arg.hdr_add.fmt, PR_MODE_HTTP);
+		parse_logformat_string(args[cur_arg + 1], proxy, &rule->arg.hdr_add.fmt, LOG_OPT_MANDATORY);
 		cur_arg += 2;
 	} else if (strcmp(args[0], "redirect") == 0) {
 		struct redirect_rule *redir;