diff --git a/repos/gems/src/app/mixer_gui_qt/main.cpp b/repos/gems/src/app/mixer_gui_qt/main.cpp
index f36b8c7e9d..97ddb49313 100644
--- a/repos/gems/src/app/mixer_gui_qt/main.cpp
+++ b/repos/gems/src/app/mixer_gui_qt/main.cpp
@@ -41,17 +41,17 @@ struct Report_handler
 	Genode::Entrypoint                     sig_ep;
 	Genode::Signal_handler<Report_handler> channels_handler;
 
-	Genode::Lock _report_lock { Genode::Lock::LOCKED };
+	Genode::Blockade _report_blockade { };
 
 	bool window_connected { false };
 
 	void _report(char const *data, size_t size)
 	{
 		Genode::Xml_node node(data, size);
-		proxy->report_changed(&_report_lock, &node);
+		proxy->report_changed(&_report_blockade, &node);
 
 		/* wait until the report was handled */
-		_report_lock.lock();
+		_report_blockade.block();
 	}
 
 	void _handle_channels()
diff --git a/repos/gems/src/app/mixer_gui_qt/main_window.cpp b/repos/gems/src/app/mixer_gui_qt/main_window.cpp
index c939eb830a..aa6de5eb0f 100644
--- a/repos/gems/src/app/mixer_gui_qt/main_window.cpp
+++ b/repos/gems/src/app/mixer_gui_qt/main_window.cpp
@@ -421,13 +421,13 @@ void Main_window::_update_clients(Genode::Xml_node &channels)
  */
 void Main_window::report_changed(void *l, void const *p)
 {
-	Genode::Lock &lock     = *reinterpret_cast<Genode::Lock*>(l);
+	Genode::Blockade &blockade = *reinterpret_cast<Genode::Blockade*>(l);
 	Genode::Xml_node &node = *((Genode::Xml_node*)p);
 
 	if (node.has_type("channel_list"))
 		_update_clients(node);
 
-	lock.unlock();
+	blockade.wakeup();
 }
 
 
diff --git a/repos/gems/src/app/mixer_gui_qt/main_window.h b/repos/gems/src/app/mixer_gui_qt/main_window.h
index a52a13332b..e6fc7d3806 100644
--- a/repos/gems/src/app/mixer_gui_qt/main_window.h
+++ b/repos/gems/src/app/mixer_gui_qt/main_window.h
@@ -16,7 +16,6 @@
 
 /* Genode includes */
 #include <base/env.h>
-#include <base/lock.h>
 #include <util/xml_node.h>
 
 /* Qt includes */