diff --git a/ffserver.c b/ffserver.c
index bc7dbee760..374af99cc7 100644
--- a/ffserver.c
+++ b/ffserver.c
@@ -373,8 +373,8 @@ static void ffm_set_write_index(AVFormatContext *s, int64_t pos,
                                 int64_t file_size)
 {
     av_opt_set_int(s, "server_attached", 1, AV_OPT_SEARCH_CHILDREN);
-    av_opt_set_int(s, "write_index", pos, AV_OPT_SEARCH_CHILDREN);
-    av_opt_set_int(s, "file_size", file_size, AV_OPT_SEARCH_CHILDREN);
+    av_opt_set_int(s, "ffm_write_index", pos, AV_OPT_SEARCH_CHILDREN);
+    av_opt_set_int(s, "ffm_file_size", file_size, AV_OPT_SEARCH_CHILDREN);
 }
 
 static char *ctime1(char *buf2, size_t buf_size)
diff --git a/libavformat/ffmdec.c b/libavformat/ffmdec.c
index 41c518f3c7..257319bd06 100644
--- a/libavformat/ffmdec.c
+++ b/libavformat/ffmdec.c
@@ -775,8 +775,8 @@ static int ffm_probe(AVProbeData *p)
 
 static const AVOption options[] = {
     {"server_attached", NULL, offsetof(FFMContext, server_attached), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, AV_OPT_FLAG_EXPORT },
-    {"ffm_write_index", NULL, offsetof(FFMContext, write_index), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, 1, AV_OPT_FLAG_EXPORT },
-    {"ffm_file_size", NULL, offsetof(FFMContext, file_size), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, 1, AV_OPT_FLAG_EXPORT },
+    {"ffm_write_index", NULL, offsetof(FFMContext, write_index), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, AV_OPT_FLAG_EXPORT },
+    {"ffm_file_size", NULL, offsetof(FFMContext, file_size), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, AV_OPT_FLAG_EXPORT },
     { NULL },
 };