diff --git a/lib/periodic_msg_source_impl.cc b/lib/periodic_msg_source_impl.cc
index add56c1..3b545c6 100644
--- a/lib/periodic_msg_source_impl.cc
+++ b/lib/periodic_msg_source_impl.cc
@@ -14,7 +14,7 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-#include <foo/periodic_msg_source.h>
+#include "periodic_msg_source_impl.h"
 
 #include <gnuradio/io_signature.h>
 #include <gnuradio/block_detail.h>
@@ -22,13 +22,10 @@
 
 using namespace gr::foo;
 
-class periodic_msg_source_impl : public periodic_msg_source {
-
 #define dout d_debug && std::cout
 
-public:
-
-periodic_msg_source_impl(pmt::pmt_t msg, float interval, int num_msg, bool debug) :
+periodic_msg_source_impl::periodic_msg_source_impl(pmt::pmt_t msg,
+			float interval, int num_msg, bool debug) :
 		block("periodic_msg_source",
 				gr::io_signature::make(0, 0, 0),
 				gr::io_signature::make(0, 0, 0)),
@@ -42,14 +39,15 @@ periodic_msg_source_impl(pmt::pmt_t msg, float interval, int num_msg, bool debug
 	d_thread = boost::shared_ptr<boost::thread>(new boost::thread(boost::bind(&periodic_msg_source_impl::run, this, this)));
 }
 
-~periodic_msg_source_impl() {
+periodic_msg_source_impl::~periodic_msg_source_impl() {
 	d_finished = true;
 	d_thread->interrupt();
 	d_thread->join();
 }
 
 
-void run(periodic_msg_source_impl *instance) {
+void
+periodic_msg_source_impl::run(periodic_msg_source_impl *instance) {
 
 	// flow graph startup delay
 	boost::this_thread::sleep(boost::posix_time::milliseconds(500));
@@ -75,16 +73,6 @@ void run(periodic_msg_source_impl *instance) {
 	message_port_pub(pmt::mp("out"), pmt::PMT_EOF);
 }
 
-private:
-	int d_num_msg;
-	bool d_debug;
-	bool d_finished;
-	float d_interval;
-	pmt::pmt_t d_msg;
-	boost::shared_ptr<boost::thread> d_thread;
-
-};
-
 periodic_msg_source::sptr
 periodic_msg_source::make(pmt::pmt_t msg, float interval, int num_msg, bool debug) {
 	return gnuradio::get_initial_sptr(new periodic_msg_source_impl(msg, interval, num_msg, debug));
diff --git a/lib/periodic_msg_source_impl.h b/lib/periodic_msg_source_impl.h
new file mode 100644
index 0000000..89cf330
--- /dev/null
+++ b/lib/periodic_msg_source_impl.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2013 Bastian Bloessl <bloessl@ccs-labs.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef INCLUDED_FOO_PERIODIC_MSG_SOURCE_IMPL_H
+#define INCLUDED_FOO_PERIODIC_MSG_SOURCE_IMPLH
+
+#include <foo/periodic_msg_source.h>
+
+namespace gr {
+namespace foo {
+
+	class periodic_msg_source_impl : public periodic_msg_source {
+		private:
+			void run(periodic_msg_source_impl *instance);
+
+			int d_num_msg;
+			bool d_debug;
+			bool d_finished;
+			float d_interval;
+			pmt::pmt_t d_msg;
+			boost::shared_ptr<boost::thread> d_thread;
+
+		public:
+			periodic_msg_source_impl(pmt::pmt_t msg,
+					float interval, int num_msg, bool debug);
+			virtual ~periodic_msg_source_impl();
+
+	};
+
+}  // namespace foo
+}  // namespace gr
+
+#endif /* INCLUDED_FOO_PERIODIC_MSG_SOURCE_IMPL_H */