diff --git a/libavformat/smoothstreamingenc.c b/libavformat/smoothstreamingenc.c
index a6d0a36c2e65d1b4c071178332a3b9d1ed7d6de8..e3e4abba4675272668e8c49ade1c30f7c0717a33 100644
--- a/libavformat/smoothstreamingenc.c
+++ b/libavformat/smoothstreamingenc.c
@@ -576,7 +576,7 @@ static int ism_write_packet(AVFormatContext *s, AVPacket *pkt)
     SmoothStreamingContext *c = s->priv_data;
     AVStream *st = s->streams[pkt->stream_index];
     OutputStream *os = &c->streams[pkt->stream_index];
-    int64_t end_dts = (c->nb_fragments + 1) * c->min_frag_duration;
+    int64_t end_dts = (c->nb_fragments + 1) * (int64_t) c->min_frag_duration;
     int ret;
 
     if (st->first_dts == AV_NOPTS_VALUE)