diff --git a/gr-jay/grc/jay_peak_detect.xml b/gr-jay/grc/jay_peak_detect.xml
index de5bbf5..38a5998 100644
--- a/gr-jay/grc/jay_peak_detect.xml
+++ b/gr-jay/grc/jay_peak_detect.xml
@@ -90,11 +90,13 @@
     <name>out</name>
     <type>float</type>
     <vlen>$vlen</vlen>
+    <optional>1</optional>
   </source>
   <source>
     <name>pbox</name>
     <type>float</type>
     <vlen>$vlen</vlen>
+    <optional>1</optional>
   </source>
   <source>
     <name>status</name>
diff --git a/gr-jay/include/jay/peak_detect.h b/gr-jay/include/jay/peak_detect.h
index 804ea2d..0c252c8 100644
--- a/gr-jay/include/jay/peak_detect.h
+++ b/gr-jay/include/jay/peak_detect.h
@@ -33,7 +33,7 @@ namespace gr {
      * \ingroup jay
      *
      */
-    class JAY_API peak_detect : virtual public gr::sync_block
+    class JAY_API peak_detect : virtual public gr::block
     {
      public:
       typedef boost::shared_ptr<peak_detect> sptr;
diff --git a/gr-jay/lib/peak_detect_impl.cc b/gr-jay/lib/peak_detect_impl.cc
index eddc240..5a4ab3d 100644
--- a/gr-jay/lib/peak_detect_impl.cc
+++ b/gr-jay/lib/peak_detect_impl.cc
@@ -39,9 +39,9 @@ namespace gr {
      * The private constructor
      */
     peak_detect_impl::peak_detect_impl(int vlen, float framerate, float bandwidth, float fcenter, float peak_height_min, int peak_width_min, int peak_width_max, float alpha_s, float alpha_m)
-		: gr::sync_block("peak_detect"
+		: gr::block("peak_detect"
 		, gr::io_signature::make(1, 1, vlen*sizeof(float))
-        , gr::io_signature::make(2, 2, vlen*sizeof(float)))
+        , gr::io_signature::make(0, 2, vlen*sizeof(float)))
 		, m_vlen(vlen)
 		, m_framerate (framerate)
 		, m_bandwidth (bandwidth)
@@ -126,23 +126,31 @@ namespace gr {
 			}
 		}
 		return result;
-	}
+		}
 
-    int
-    peak_detect_impl::work(int noutput_items,
-        gr_vector_const_void_star &input_items,
-        gr_vector_void_star &output_items)
+	void peak_detect_impl::forecast(int noutput_items, gr_vector_int& ninput_items_required)
+	{
+		ninput_items_required[0] = noutput_items;
+	}
+	
+	int peak_detect_impl::general_work (int noutput_items, gr_vector_int &ninput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
     {
 		const int DATA = 0;
 		const int PBOX = 1;
-		
+
 		int nitems_per_block = this->output_signature()->sizeof_stream_item(0)/sizeof(float);
 
 		float *iptr = (float *)input_items[DATA];
-		float *optr_data = (float *)output_items[DATA];
-		float *optr_pbox = (float *)output_items[PBOX];
+		float *optr_data = nullptr;
+		float *optr_pbox = nullptr;
+	
+		if (output_items.size() > 0)
+		{
+			optr_data = (float *)output_items[DATA];
+			optr_pbox = (float *)output_items[PBOX];
+		}
 		
-		for (int k = 0; k < noutput_items; k++)
+		for (int k = 0; k < ninput_items[DATA]; k++)
 		{
 			// Initialization on first frame
 			if (m_frameCount == 0)
@@ -369,13 +377,23 @@ namespace gr {
 			// -----------------------------------------------------------------
 			// Output peak box data
 			// -----------------------------------------------------------------
-			for (int i = 0; i < nitems_per_block; i++)
+			if (optr_data)
 			{
-				*(optr_data++) = m_pXs[i];
-				*(optr_pbox++) = m_pPeakBox_abs[i];
+				for (int i = 0; i < nitems_per_block; i++)
+				{
+					*(optr_data++) = m_pXs[i];
+				}
+			}
+			if (optr_pbox)
+			{
+				for (int i = 0; i < nitems_per_block; i++)
+				{
+					*(optr_pbox++) = m_pPeakBox_abs[i];
+				}
 			}
 
 			m_frameCount++;
+			consume(0, ninput_items[DATA]);
 		}
 
 		// Tell runtime system how many output items we produced.
diff --git a/gr-jay/lib/peak_detect_impl.h b/gr-jay/lib/peak_detect_impl.h
index a51b1ee..4f61d7b 100644
--- a/gr-jay/lib/peak_detect_impl.h
+++ b/gr-jay/lib/peak_detect_impl.h
@@ -326,7 +326,9 @@ namespace jay {
 		~peak_detect_impl();
 
 		// Where all the action really happens
-		int work(int noutput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items);
+		int general_work (int noutput_items, gr_vector_int &ninput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items);
+		void forecast (int noutput_items, gr_vector_int &ninput_items_required);
+		
 	private:
 		void fill(float *pDst, int length, float value);
 		float mean(float *pSrc, int length);