diff --git a/libavformat/rpl.c b/libavformat/rpl.c
index d025589bfc..3ef6fda386 100644
--- a/libavformat/rpl.c
+++ b/libavformat/rpl.c
@@ -279,7 +279,7 @@ static int rpl_read_header(AVFormatContext *s)
     error |= read_line(pb, line, sizeof(line));  // size of "helpful" sprite
     if (vst) {
         error |= read_line(pb, line, sizeof(line));  // offset to key frame list
-        vst->duration = number_of_chunks * rpl->frames_per_chunk;
+        vst->duration = number_of_chunks * (int64_t)rpl->frames_per_chunk;
     }
 
     // Read the index