diff --git a/libavcodec/truemotion2rt.c b/libavcodec/truemotion2rt.c
index 94d44800b2..d63918742d 100644
--- a/libavcodec/truemotion2rt.c
+++ b/libavcodec/truemotion2rt.c
@@ -63,7 +63,8 @@ static int truemotion2rt_decode_header(AVCodecContext *avctx, const AVPacket *av
     uint8_t header_buffer[128] = { 0 };  /* logical maximum header size */
     const uint8_t *buf = avpkt->data;
     int size = avpkt->size;
-    int i;
+    int width, height;
+    int ret, i;
 
     if (size < 1) {
         av_log(avctx, AV_LOG_ERROR, "input packet too small (%d)\n", size);
@@ -90,8 +91,12 @@ static int truemotion2rt_decode_header(AVCodecContext *avctx, const AVPacket *av
     if (s->delta_size < 2 || s->delta_size > 4)
         return AVERROR_INVALIDDATA;
 
-    avctx->height = AV_RL16(header_buffer + 5);
-    avctx->width  = AV_RL16(header_buffer + 7);
+    height = AV_RL16(header_buffer + 5);
+    width  = AV_RL16(header_buffer + 7);
+
+    ret = ff_set_dimensions(avctx, width, height);
+    if (ret < 0)
+        return ret;
 
     av_log(avctx, AV_LOG_DEBUG, "Header size: %d\n", header_size);
     return header_size;