diff --git a/mj2/extract_j2k_from_mj2.c b/mj2/extract_j2k_from_mj2.c
index 86ce02ad..adf81393 100644
--- a/mj2/extract_j2k_from_mj2.c
+++ b/mj2/extract_j2k_from_mj2.c
@@ -16,7 +16,8 @@ jmp_buf j2k_error;
 
 int main(int argc, char *argv[]) {
 
-  unsigned int tnum, snum;
+  int tnum;
+  unsigned int snum;
   mj2_movie_t movie;
   mj2_tk_t *track;
   mj2_sample_t *sample;
@@ -40,6 +41,8 @@ int main(int argc, char *argv[]) {
   if (mj2_read_struct(file, &movie)) // Creating the movie structure
     return 1;
 
+  mj2_init_stdmovie(&movie);
+
   // Decode first video track 
   tnum = 0;
   while (movie.tk[tnum].track_type != 0)