diff --git a/source/Makefile.mk b/source/Makefile.mk
index 8e2aa9d2d..c88a7d615 100644
--- a/source/Makefile.mk
+++ b/source/Makefile.mk
@@ -55,7 +55,7 @@ BASE_FLAGS += -Wcast-align -Wunsafe-loop-optimizations
 endif
 ifeq ($(LINUX),true)
 CFLAGS     += -isystem /opt/kxstudio/include
-CXXFLAGS   += -isystem /opt/kxstudio/include -isystem /usr/include/qt5
+CXXFLAGS   += -isystem /opt/kxstudio/include -isystem /usr/include/qt4
 endif
 ifeq ($(MACOS),true)
 CFLAGS     += -isystem /opt/local/include/
diff --git a/source/backend/engine/CarlaEngineJack.cpp b/source/backend/engine/CarlaEngineJack.cpp
index 59d2090d4..d15a49e93 100644
--- a/source/backend/engine/CarlaEngineJack.cpp
+++ b/source/backend/engine/CarlaEngineJack.cpp
@@ -77,10 +77,10 @@ public:
         case ENGINE_PROCESS_MODE_SINGLE_CLIENT:
         case ENGINE_PROCESS_MODE_MULTIPLE_CLIENTS:
             CARLA_SAFE_ASSERT_RETURN(jackClient != nullptr && jackPort != nullptr,);
-
+#ifndef CARLA_OS_WIN
             if (const jack_uuid_t uuid = jackbridge_port_uuid(jackPort))
                 jackbridge_set_property(jackClient, uuid, URI_CANVAS_CV, "NO", "text/plain");
-
+#endif
             break;
 
         default:
@@ -95,8 +95,10 @@ public:
 
         if (fJackClient != nullptr && fJackPort != nullptr)
         {
+#ifndef CARLA_OS_WIN
             if (const jack_uuid_t uuid = jackbridge_port_uuid(fJackPort))
                 jackbridge_remove_property(fJackClient, uuid, URI_CANVAS_CV);
+#endif
 
             try {
                 jackbridge_port_unregister(fJackClient, fJackPort);
@@ -163,10 +165,10 @@ public:
         case ENGINE_PROCESS_MODE_SINGLE_CLIENT:
         case ENGINE_PROCESS_MODE_MULTIPLE_CLIENTS:
             CARLA_SAFE_ASSERT_RETURN(jackClient != nullptr && jackPort != nullptr,);
-
+#ifndef CARLA_OS_WIN
             if (const jack_uuid_t uuid = jackbridge_port_uuid(jackPort))
                 jackbridge_set_property(jackClient, uuid, URI_CANVAS_CV, "YES", "text/plain");
-
+#endif
             break;
 
         default:
@@ -181,8 +183,10 @@ public:
 
         if (fJackClient != nullptr && fJackPort != nullptr)
         {
+#ifndef CARLA_OS_WIN
             if (const jack_uuid_t uuid = jackbridge_port_uuid(fJackPort))
                 jackbridge_remove_property(fJackClient, uuid, URI_CANVAS_CV);
+#endif
 
             try {
                 jackbridge_port_unregister(fJackClient, fJackPort);