diff --git a/docs/hfcs.1 b/docs/hfcs.1
index 5a7af15..9b1cf88 100644
--- a/docs/hfcs.1
+++ b/docs/hfcs.1
@@ -52,6 +52,8 @@ fields as well.
 Regular expression match against the post
 .Fa content .
 The special value of "." will match any post with a summary only.
+.It Ar is reply
+A reply to another post.
 .It Ar is announce
 Is announced (shared).
 .It Ar announce of
diff --git a/hfcs.go b/hfcs.go
index ec82ecc..d51e541 100644
--- a/hfcs.go
+++ b/hfcs.go
@@ -33,6 +33,7 @@ type Filter struct {
 	IncludeAudience bool   `json:",omitempty"`
 	Text            string `json:",omitempty"`
 	re_text         *regexp.Regexp
+	IsReply         bool   `json:",omitempty"`
 	IsAnnounce      bool   `json:",omitempty"`
 	AnnounceOf      string `json:",omitempty"`
 	Reject          bool   `json:",omitempty"`
@@ -306,6 +307,13 @@ func matchfilterX(h *Honk, f *Filter) string {
 			}
 		}
 	}
+	if match && f.IsReply {
+		match = false
+		if h.RID != "" {
+			match = true
+			rv += " reply"
+		}
+	}
 	if match && f.IsAnnounce {
 		match = false
 		if (f.AnnounceOf == "" && h.Oonker != "") || f.AnnounceOf == h.Oonker ||
diff --git a/views/hfcs.html b/views/hfcs.html
index b6f436d..8b2e534 100644
--- a/views/hfcs.html
+++ b/views/hfcs.html
@@ -20,6 +20,8 @@ Honk Filtering and Censorship System
 <input tabindex=1 type="checkbox" id="incaud" name="incaud" value="yes"><span></span></label></span>
 <p><label for="filttext">text matches:</label><br>
 <input tabindex=1 type="text" name="filttext" value="" autocomplete=off>
+<p><span><label class=button for="isreply">is reply:
+<input tabindex=1 type="checkbox" id="isreply" name="isreply" value="yes"><span></span></label></span>
 <p><span><label class=button for="isannounce">is announce:
 <input tabindex=1 type="checkbox" id="isannounce" name="isannounce" value="yes"><span></span></label></span>
 <p><label for="announceof">announce of:</label><br>
@@ -54,6 +56,7 @@ Honk Filtering and Censorship System
 {{ with .Notes }}<p>Notes: {{ . }}{{ end }}
 <p>Date: {{ .Date.Format "2006-01-02" }}
 {{ with .Actor }}<p>Who: {{ . }}{{ end }} {{ with .IncludeAudience }} (inclusive) {{ end }}
+{{ if .IsReply }}<p>Reply: y{{ end }}
 {{ if .IsAnnounce }}<p>Announce: {{ .AnnounceOf }}{{ end }}
 {{ with .Text }}<p>Text: {{ . }}{{ end }}
 <p>Actions: {{ range .Actions }} {{ . }} {{ end }}
diff --git a/web.go b/web.go
index e883f73..7f5f30f 100644
--- a/web.go
+++ b/web.go
@@ -2004,6 +2004,7 @@ func savehfcs(w http.ResponseWriter, r *http.Request) {
 	filt.Actor = strings.TrimSpace(r.FormValue("actor"))
 	filt.IncludeAudience = r.FormValue("incaud") == "yes"
 	filt.Text = strings.TrimSpace(r.FormValue("filttext"))
+	filt.IsReply = r.FormValue("isreply") == "yes"
 	filt.IsAnnounce = r.FormValue("isannounce") == "yes"
 	filt.AnnounceOf = strings.TrimSpace(r.FormValue("announceof"))
 	filt.Reject = r.FormValue("doreject") == "yes"