Index: head/lib/libsbuf/Symbol.map
===================================================================
--- head/lib/libsbuf/Symbol.map
+++ head/lib/libsbuf/Symbol.map
@@ -37,6 +37,9 @@
 
 FBSD_1.5 {
 	sbuf_putbuf;
-	sbuf_printf_drain;
 };
 
+/* Added in FreeBSD 13.x */
+FBSD_1.6 {
+	sbuf_printf_drain;
+};
Index: head/lib/libsbuf/Version.def
===================================================================
--- head/lib/libsbuf/Version.def
+++ head/lib/libsbuf/Version.def
@@ -11,3 +11,7 @@
 
 FBSD_1.5 {
 } FBSD_1.4;
+
+# This version was first added to 13.0-current.
+FBSD_1.6 {
+} FBSD_1.5;