diff --git a/doc/APIchanges b/doc/APIchanges
index a58de69b42..6ec3dae809 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -13,6 +13,13 @@ libavutil:   2009-03-08
 
 API changes, most recent first:
 
+2010-08-11 - r24765 - lavfi 1.33.0 - avfilter_open()
+  Change avfilter_open() signature:
+  AVFilterContext *avfilter_open(AVFilter *filter, const char *inst_name) ->
+  int avfilter_open(AVFilterContext **filter_ctx, AVFilter *filter, const char *inst_name);
+
+  This change breaks libavfilter API/ABI.
+
 2010-08-11 - r24763 - lavfi 1.32.0 - AVFilterBufferRef
   Add a type field to AVFilterBufferRef, and move video specific
   properties to AVFilterBufferRefVideoProps.