diff --git a/sbin/hastd/subr.c b/sbin/hastd/subr.c
index 24d6dd51441d..213dcd27b869 100644
--- a/sbin/hastd/subr.c
+++ b/sbin/hastd/subr.c
@@ -38,6 +38,9 @@ __FBSDID("$FreeBSD$");
 #include <errno.h>
 #include <fcntl.h>
 #include <pwd.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
 #include <unistd.h>
 
 #include <pjdlog.h>
@@ -45,6 +48,27 @@ __FBSDID("$FreeBSD$");
 #include "hast.h"
 #include "subr.h"
 
+int
+vsnprlcat(char *str, size_t size, const char *fmt, va_list ap)
+{
+	size_t len;
+
+	len = strlen(str);
+	return (vsnprintf(str + len, size - len, fmt, ap));
+}
+
+int
+snprlcat(char *str, size_t size, const char *fmt, ...)
+{
+	va_list ap;
+	int result;
+
+	va_start(ap, fmt);
+	result = vsnprlcat(str, size, fmt, ap);
+	va_end(ap);
+	return (result);
+}
+
 int
 provinfo(struct hast_resource *res, bool dowrite)
 {
diff --git a/sbin/hastd/subr.h b/sbin/hastd/subr.h
index 913d2a424c3c..0b9b55557af1 100644
--- a/sbin/hastd/subr.h
+++ b/sbin/hastd/subr.h
@@ -45,6 +45,9 @@
 	errno = _rerrno;						\
 } while (0)
 
+int vsnprlcat(char *str, size_t size, const char *fmt, va_list ap);
+int snprlcat(char *str, size_t size, const char *fmt, ...);
+
 int provinfo(struct hast_resource *res, bool dowrite);
 const char *role2str(int role);
 int drop_privs(void);