diff --git a/doc/filters.texi b/doc/filters.texi
index c70ddf3b50..01eb8935b8 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -4447,6 +4447,10 @@ and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
 which @code{fieldmatch} is based on. While the semantic and usage are very
 close, some behaviour and options names can differ.
 
+The filter currently only works for constant frame rate input. Do not use it
+if your input has mixed telecined and progressive content with changing
+framerate.
+
 The filter accepts the following options:
 
 @table @option