diff --git a/platform/BufferedSerial.cpp b/platform/BufferedSerial.cpp
index 5568491192..99ca8527f0 100644
--- a/platform/BufferedSerial.cpp
+++ b/platform/BufferedSerial.cpp
@@ -40,7 +40,7 @@ BufferedSerial::~BufferedSerial()
 
 void BufferedSerial::DCD_IRQ()
 {
-    _poll_change(this);
+    wake();
 }
 
 void BufferedSerial::set_data_carrier_detect(PinName DCD_pin, bool active_high)
@@ -94,6 +94,18 @@ int BufferedSerial::sync()
     return 0;
 }
 
+void BufferedSerial::sigio(Callback<void()> func) {
+    core_util_critical_section_enter();
+    _sigio_cb = func;
+    if (_sigio_cb) {
+        short current_events = poll(0x7FFF);
+        if (current_events) {
+            _sigio_cb();
+        }
+    }
+    core_util_critical_section_exit();
+}
+
 ssize_t BufferedSerial::write(const void* buffer, size_t length)
 {
     size_t data_written = 0;
@@ -164,6 +176,14 @@ bool BufferedSerial::hup() const
     return _dcd && _dcd->read() != 0;
 }
 
+void BufferedSerial::wake()
+{
+    _poll_change(this);
+    if (_sigio_cb) {
+        _sigio_cb();
+    }
+}
+
 short BufferedSerial::poll(short events) const {
 
     short revents = 0;
@@ -213,7 +233,7 @@ void BufferedSerial::rx_irq(void)
 
     /* Report the File handler that data is ready to be read from the buffer. */
     if (was_empty && !_rxbuf.empty()) {
-        _poll_change(this);
+        wake();
     }
 }
 
@@ -237,7 +257,7 @@ void BufferedSerial::tx_irq(void)
 
     /* Report the File handler that data can be written to peripheral. */
     if (was_full && !_txbuf.full() && !hup()) {
-        _poll_change(this);
+        wake();
     }
 }
 
diff --git a/platform/BufferedSerial.h b/platform/BufferedSerial.h
index 6a8cfe17ec..998a30d359 100644
--- a/platform/BufferedSerial.h
+++ b/platform/BufferedSerial.h
@@ -64,8 +64,11 @@ public:
 
     virtual int set_blocking(bool blocking) { _blocking = blocking; return 0; }
 
+    virtual void sigio(Callback<void()> func);
+
     void set_data_carrier_detect(PinName DCD_pin, bool active_high=false);
 
+
 private:
 
     /** Software serial buffers
@@ -76,6 +79,8 @@ private:
 
     PlatformMutex _mutex;
 
+    Callback<void()> _sigio_cb;
+
     bool _blocking;
     bool _tx_irq_enabled;
     InterruptIn *_dcd;
@@ -95,6 +100,8 @@ private:
     void tx_irq(void);
     void rx_irq(void);
 
+    void wake(void);
+
     void DCD_IRQ(void);
 };
 } //namespace mbed
diff --git a/platform/FileHandle.cpp b/platform/FileHandle.cpp
index 09d5e0834d..df72616993 100644
--- a/platform/FileHandle.cpp
+++ b/platform/FileHandle.cpp
@@ -32,19 +32,6 @@ off_t FileHandle::size()
     seek(off, SEEK_SET);
     return size;
 }
-
-void FileHandle::sigio(Callback<void()> func) {
-    core_util_critical_section_enter();
-    _callback = func;
-    if (_callback) {
-        short current_events = poll(0x7FFF);
-        if (current_events) {
-            _callback();
-        }
-    }
-    core_util_critical_section_exit();
-}
-
 std::FILE *fdopen(FileHandle *fh, const char *mode)
 {
     return mbed_fdopen(fh, mode);
diff --git a/platform/FileHandle.h b/platform/FileHandle.h
index bc3d31d685..5123cbde2b 100644
--- a/platform/FileHandle.h
+++ b/platform/FileHandle.h
@@ -181,7 +181,9 @@ public:
      * The input parameter can be used or ignored - the could always return all events,
      * or could check just the events listed in events.
      * Call is non-blocking - returns instantaneous state of events.
-     * Whenever an event occurs, the derived class must call _poll_change().
+     * Whenever an event occurs, the derived class must call _poll_change() (as well as
+     * the sigio() callback).
+     *
      * @param events bitmask of poll events we're interested in - POLLIN/POLLOUT etc.
      *
      * @returns
@@ -230,18 +232,10 @@ public:
      *
      *  @param func     Function to call on state change
      */
-    void sigio(Callback<void()> func);
-
-    /** Issue sigio to user - used by mbed::_poll_change */
-    void _send_sigio()
+    virtual void sigio(Callback<void()> func)
     {
-        if (_callback) {
-            _callback();
-        }
+        //Default for real files. Do nothing for real files.
     }
-
-private:
-    Callback<void()> _callback;
 };
 
 /** Not a member function
diff --git a/platform/mbed_poll.cpp b/platform/mbed_poll.cpp
index ffe426533b..41e4bf1f22 100644
--- a/platform/mbed_poll.cpp
+++ b/platform/mbed_poll.cpp
@@ -75,9 +75,6 @@ int poll(pollfh fhs[], unsigned nfhs, int timeout)
 void _poll_change(FileHandle *fh)
 {
     // TODO, will depend on how we implement poll
-
-    // Also, do the user callback
-    fh->_send_sigio();
 }
 
 } // namespace mbed
diff --git a/platform/mbed_poll.h b/platform/mbed_poll.h
index fd360ba620..3aea995d6e 100644
--- a/platform/mbed_poll.h
+++ b/platform/mbed_poll.h
@@ -49,7 +49,9 @@ struct pollfh {
  */
 int poll(pollfh fhs[], unsigned nfhs, int timeout);
 
-/** To be called by device when poll state changes - must be called for poll() and sigio() to work
+/** To be called by device when poll state changes - must be called for poll() to work
+ * This must be called in addition to the user-provided callback.
+ *
  * @param fh    A pointer to the file handle*/
 void _poll_change(FileHandle *fh);