4 files changed, 41 insertions, 5 deletions
diff --git a/gr-blocks/grc/blocks_null_sink.xml b/gr-blocks/grc/blocks_null_sink.xml
index 2ae20e619a..f2907d20bd 100644
--- a/gr-blocks/grc/blocks_null_sink.xml
+++ b/gr-blocks/grc/blocks_null_sink.xml
@@ -45,10 +45,27 @@
 		<value>1</value>
 		<type>int</type>
 	</param>
+	<param>
+		<name>Num Inputs</name>
+		<key>num_inputs</key>
+		<value>1</value>
+		<type>int</type>
+	</param>
+	<param>
+		<name>Bus Connections</name>
+		<key>bus_conns</key>
+                <value>[[0,],]</value>
+		<type>raw</type>
+                <hide>part</hide>
+	</param>
+	<check>$num_inputs &gt;= 1</check>
 	<check>$vlen &gt; 0</check>
 	<sink>
 		<name>in</name>
 		<type>$type</type>
 		<vlen>$vlen</vlen>
+		<nports>$num_inputs</nports>
 	</sink>
+        <bus_structure_sink>$bus_conns</bus_structure_sink>
 </block>
+
diff --git a/gr-blocks/grc/blocks_null_source.xml b/gr-blocks/grc/blocks_null_source.xml
index 01d3905cab..9c109e651f 100644
--- a/gr-blocks/grc/blocks_null_source.xml
+++ b/gr-blocks/grc/blocks_null_source.xml
@@ -45,10 +45,26 @@
 		<value>1</value>
 		<type>int</type>
 	</param>
+	<param>
+		<name>Num Outputs</name>
+		<key>num_outputs</key>
+		<value>1</value>
+		<type>int</type>
+	</param>
+	<param>
+		<name>Bus Connections</name>
+		<key>bus_conns</key>
+                <value>[[0,],]</value>
+		<type>raw</type>
+                <hide>part</hide>
+	</param>
+	<check>$num_outputs &gt;= 1</check>
 	<check>$vlen &gt; 0</check>
 	<source>
 		<name>out</name>
 		<type>$type</type>
 		<vlen>$vlen</vlen>
+		<nports>$num_outputs</nports>
 	</source>
+        <bus_structure_source>$bus_conns</bus_structure_source>
 </block>
diff --git a/gr-blocks/lib/null_sink_impl.cc b/gr-blocks/lib/null_sink_impl.cc
index 41adeea0fd..14dd5eff24 100644
--- a/gr-blocks/lib/null_sink_impl.cc
+++ b/gr-blocks/lib/null_sink_impl.cc
@@ -39,8 +39,8 @@ namespace gr {
 
     null_sink_impl::null_sink_impl(size_t sizeof_stream_item)
       : sync_block("null_sink",
-                      io_signature::make(1, 1, sizeof_stream_item),
-                      io_signature::make(0, 0, 0))
+                   io_signature::make(1, -1, sizeof_stream_item),
+                   io_signature::make(0, 0, 0))
     {
     }
 
diff --git a/gr-blocks/lib/null_source_impl.cc b/gr-blocks/lib/null_source_impl.cc
index edf0104da1..9550dd6bce 100644
--- a/gr-blocks/lib/null_source_impl.cc
+++ b/gr-blocks/lib/null_source_impl.cc
@@ -41,7 +41,7 @@ namespace gr {
     null_source_impl::null_source_impl (size_t sizeof_stream_item)
       : sync_block("null_source",
                       io_signature::make(0, 0, 0),
-                      io_signature::make(1, 1, sizeof_stream_item))
+                      io_signature::make(1, -1, sizeof_stream_item))
     {
     }
 
@@ -54,8 +54,11 @@ namespace gr {
                            gr_vector_const_void_star &input_items,
                            gr_vector_void_star &output_items)
     {
-      void *optr = (void*)output_items[0];
-      memset(optr, 0, noutput_items * output_signature()->sizeof_stream_item(0));
+      void *optr;
+      for(size_t n = 0; n < input_items.size(); n++) {
+        optr = (void*)output_items[n];
+        memset(optr, 0, noutput_items * output_signature()->sizeof_stream_item(n));
+      }
       return noutput_items;
     }