diff --git a/libavcodec/opt.c b/libavcodec/opt.c
index a6abcfc2e7..3a6f1f7146 100644
--- a/libavcodec/opt.c
+++ b/libavcodec/opt.c
@@ -408,6 +408,19 @@ int av_opt_show(void *obj, void *av_log_obj){
 void av_opt_set_defaults2(void *s, int mask, int flags)
 {
     const AVOption *opt = NULL;
+
+    if(   sizeof(AVOption) != sizeof(AVOption2)
+       || offsetof(AVOption,default_val) != offsetof(AVOption2,default_val.dbl)
+       || offsetof(AVOption,min) != offsetof(AVOption2,min)
+    ){
+        av_log(NULL, AV_LOG_ERROR, "AVOpt1/2 missmatch %zd %zd %td %td %td %td\n",
+               sizeof(AVOption), sizeof(AVOption2),
+               offsetof(AVOption,default_val), offsetof(AVOption2,default_val.dbl),
+               offsetof(AVOption,min), offsetof(AVOption2,min));
+#undef exit
+        exit(123);
+    }
+
     while ((opt = av_next_option(s, opt)) != NULL) {
         if((opt->flags & mask) != flags)
             continue;