diff --git a/plugin/client.go b/plugin/client.go
index dca1a52..5e96006 100644
--- a/plugin/client.go
+++ b/plugin/client.go
@@ -79,7 +79,7 @@ func (r *Recipient) WrapWithLabels(fileKey []byte) (stanzas []*age.Stanza, label
 	if err := writeStanza(conn, addType, r.encoding); err != nil {
 		return nil, nil, err
 	}
-	if err := writeStanza(conn, fmt.Sprintf("grease-%x", rand.Int())); err != nil {
+	if _, err := writeGrease(conn); err != nil {
 		return nil, nil, err
 	}
 	if err := writeStanzaWithBody(conn, "wrap-file-key", fileKey); err != nil {
@@ -220,7 +220,7 @@ func (i *Identity) Unwrap(stanzas []*age.Stanza) (fileKey []byte, err error) {
 	if err := writeStanza(conn, "add-identity", i.encoding); err != nil {
 		return nil, err
 	}
-	if err := writeStanza(conn, fmt.Sprintf("grease-%x", rand.Int())); err != nil {
+	if _, err := writeGrease(conn); err != nil {
 		return nil, err
 	}
 	for _, rs := range stanzas {
@@ -449,3 +449,18 @@ func writeStanzaWithBody(conn io.Writer, t string, body []byte) error {
 	s := &format.Stanza{Type: t, Body: body}
 	return s.Marshal(conn)
 }
+
+func writeGrease(conn io.Writer) (sent bool, err error) {
+	if rand.Intn(3) == 0 {
+		return false, nil
+	}
+	s := &format.Stanza{Type: fmt.Sprintf("grease-%x", rand.Int())}
+	for i := 0; i < rand.Intn(3); i++ {
+		s.Args = append(s.Args, fmt.Sprintf("%d", rand.Intn(100)))
+	}
+	if rand.Intn(2) == 0 {
+		s.Body = make([]byte, rand.Intn(100))
+		rand.Read(s.Body)
+	}
+	return true, s.Marshal(conn)
+}
diff --git a/plugin/plugin.go b/plugin/plugin.go
index 5a265d8..55c697b 100644
--- a/plugin/plugin.go
+++ b/plugin/plugin.go
@@ -251,6 +251,14 @@ ReadLoop:
 		}
 	}
 
+	if sent, err := writeGrease(os.Stdout); err != nil {
+		return fatalf("failed to write grease: %v", err)
+	} else if sent {
+		if err := expectUnsupported(sr); err != nil {
+			return fatalf("%v", err)
+		}
+	}
+
 	if supportsLabels {
 		if err := writeStanza(os.Stdout, "labels", labels...); err != nil {
 			return fatalf("failed to write labels stanza: %v", err)
@@ -271,6 +279,13 @@ ReadLoop:
 				return fatalf("%v", err)
 			}
 		}
+		if sent, err := writeGrease(os.Stdout); err != nil {
+			return fatalf("failed to write grease: %v", err)
+		} else if sent {
+			if err := expectUnsupported(sr); err != nil {
+				return fatalf("%v", err)
+			}
+		}
 	}
 
 	if err := writeStanza(os.Stdout, "done"); err != nil {
@@ -374,6 +389,14 @@ ReadLoop:
 	}
 
 	for i, ss := range files {
+		if sent, err := writeGrease(os.Stdout); err != nil {
+			return fatalf("failed to write grease: %v", err)
+		} else if sent {
+			if err := expectUnsupported(sr); err != nil {
+				return fatalf("%v", err)
+			}
+		}
+
 		// TODO: there should be a mechanism to let the plugin decide the order
 		// in which identities are tried.
 		for _, id := range identities {
@@ -451,6 +474,17 @@ func expectOk(sr *format.StanzaReader) error {
 	return expectStanzaWithNoBody(ok, 0)
 }
 
+func expectUnsupported(sr *format.StanzaReader) error {
+	unsupported, err := sr.ReadStanza()
+	if err != nil {
+		return fmt.Errorf("failed to read unsupported stanza: %v", err)
+	}
+	if unsupported.Type != "unsupported" {
+		return fmt.Errorf("expected unsupported stanza, got %q", unsupported.Type)
+	}
+	return expectStanzaWithNoBody(unsupported, 0)
+}
+
 func writeError(sr *format.StanzaReader, args []string, err error) error {
 	s := &format.Stanza{Type: "error", Args: args}
 	s.Body = []byte(err.Error())