Doh, somehow managed to miss the warnings from these missing includes :(

- Should've been in commit 70f063cb77

lib/formats.c

@@ -12,6 +12,7 @@
 #include <rpm/rpmfi.h>
 #include <rpm/rpmstring.h>
 #include <rpm/rpmmacro.h>
+#include <rpm/rpmbase64.h>
 
 #include "rpmio/digest.h"
 #include "lib/manifest.h"

lib/rpmts.c

@@ -13,6 +13,7 @@
 #include <rpm/rpmfileutil.h>		/* rpmtsOpenDB() needs rpmGetPath */
 #include <rpm/rpmstring.h>
 #include <rpm/rpmkeyring.h>
+#include <rpm/rpmbase64.h>
 
 #include <rpm/rpmdb.h>
 #include <rpm/rpmds.h>

rpmio/rpmpgp.c

@@ -9,6 +9,7 @@
 #include <netinet/in.h>
 #include <rpm/rpmstring.h>
 #include <rpm/rpmlog.h>
+#include <rpm/rpmbase64.h>
 
 #include "rpmio/digest.h"
 #include "rpmio/rpmio_internal.h"	/* XXX rpmioSlurp */