diff --git a/morse.cpp b/morse.cpp
index 2ee9eed..45f327a 100644
--- a/morse.cpp
+++ b/morse.cpp
@@ -32,11 +32,11 @@ export class Morse {
     : unit (ms), led (pin) {
       sys::init ();
     }
-    void operator<< (const char * text) const;
+    const Morse & operator<< (const char * text) const;
   protected:
     void out (const morse_byte mb) const;
 };
-void Morse::operator<< (const char * text) const {
+const Morse & Morse::operator<< (const char * text) const {
   const unsigned len = slen (text);
   for (unsigned n=0; n<len; n++) {
     const char c = text [n];
@@ -54,6 +54,7 @@ void Morse::operator<< (const char * text) const {
     out (mb);
   }
   sys::delay (10 * unit);
+  return * this;
 }
 /* .                    => 1 x unit
  * -                    => 3 x unit