diff --git a/doc/filters.texi b/doc/filters.texi
index 2818bd28b0..e84d7d5554 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -31911,9 +31911,9 @@ This filter accepts the following options:
 The expression which is evaluated for each frame to construct its timestamp.
 
 @item strip_fps (@emph{video only})
-Boolean option which determines if the original framerate metadata is unset.
-If set to true, be advised that a sane frame rate should be explicitly
-specified if output is sent to a constant frame rate muxer.
+Boolean option which determines if the original framerate and frame duration
+metadata is unset. If set to true, be advised that a sane frame rate should be
+explicitly specified if output is sent to a constant frame rate muxer.
 Default is @code{false}.
 
 @end table
diff --git a/libavfilter/setpts.c b/libavfilter/setpts.c
index 0565533ed2..b49a0cb64f 100644
--- a/libavfilter/setpts.c
+++ b/libavfilter/setpts.c
@@ -199,7 +199,8 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
 
     d = eval_pts(setpts, inlink, frame, frame->pts);
     frame->pts = D2TS(d);
-    frame->duration = 0;
+    if (setpts->strip_fps)
+        frame->duration = 0;
 
     av_log(inlink->dst, AV_LOG_TRACE,
             "N:%"PRId64" PTS:%s T:%f",