diff --git a/libavformat/subfile.c b/libavformat/subfile.c
index 2f162e0a34..13ee31f849 100644
--- a/libavformat/subfile.c
+++ b/libavformat/subfile.c
@@ -125,9 +125,9 @@ static int64_t subfile_seek(URLContext *h, int64_t pos, int whence)
             return end;
     }
 
-    if (whence == AVSEEK_SIZE)
-        return end - c->start;
     switch (whence) {
+    case AVSEEK_SIZE:
+        return end - c->start;
     case SEEK_SET:
         new_pos = c->start + pos;
         break;