diff --git a/libtransmission/torrent.c b/libtransmission/torrent.c
index 3fb429d9e..77e80273d 100644
--- a/libtransmission/torrent.c
+++ b/libtransmission/torrent.c
@@ -1160,12 +1160,16 @@ tr_torrentSetFilePriority( tr_torrent_t   * tor,
 }
 
 void
-tr_torrentSetFilePriorities( tr_torrent_t         * tor,
-                             const tr_priority_t  * filePriorities )
+tr_torrentSetFilePriorities( tr_torrent_t        * tor,
+                             int                 * files,
+                             int                   fileCount,
+                             tr_priority_t         priority )
 {
     int i;
-    for( i=0; i<tor->info.pieceCount; ++i )
-        tr_torrentSetFilePriorityImpl( tor, i, filePriorities[i], FALSE );
+    for( i=0; i<fileCount; ++i ) {
+        const int fileIndex = files[i];
+        tr_torrentSetFilePriorityImpl( tor, fileIndex, priority, FALSE );
+    }
     fastResumeSave( tor );
 }
 
diff --git a/libtransmission/transmission.h b/libtransmission/transmission.h
index 383c9d547..e503719fa 100644
--- a/libtransmission/transmission.h
+++ b/libtransmission/transmission.h
@@ -213,9 +213,12 @@ enum
 
 typedef int8_t tr_priority_t;
 
-/* priorities should be an array of tor->info.fileCount bytes,
- * each holding a value of TR_PRI_NORMAL, _HIGH, or _LOW */
-void tr_torrentSetFilePriorities ( tr_torrent_t *, const tr_priority_t * priorities );
+/* set a batch of files to a particular priority. */
+void tr_torrentSetFilePriorities( tr_torrent_t        * tor,
+                                  int                 * files,
+                                  int                   fileCount,
+                                  tr_priority_t         priority );
+
 
 /* single-file form of tr_torrentPrioritizeFiles.
  * priority must be one of TR_PRI_NORMAL, _HIGH, or _LOW */