diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index c805f60..af1c256 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -166,6 +166,7 @@
  * The dso__data_* external interface provides following functions:
  *   dso__data_fd
  *   dso__data_close
+ *   dso__data_size
  *   dso__data_read_offset
  *   dso__data_read_addr
  *
@@ -203,6 +204,7 @@
 int dso__data_fd(struct dso *dso, struct machine *machine);
 void dso__data_close(struct dso *dso);
 
+off_t dso__data_size(struct dso *dso, struct machine *machine);
 ssize_t dso__data_read_offset(struct dso *dso, struct machine *machine,
 			      u64 offset, u8 *data, ssize_t size);
 ssize_t dso__data_read_addr(struct dso *dso, struct map *map,