diff --git a/repos/ports/lib/mk/spec/hw_x86_64_muen/virtualbox-hwaccl.mk b/repos/ports/lib/mk/spec/hw_x86_64_muen/virtualbox-hwaccl.mk
index 81d24a546f..15717bfad2 100644
--- a/repos/ports/lib/mk/spec/hw_x86_64_muen/virtualbox-hwaccl.mk
+++ b/repos/ports/lib/mk/spec/hw_x86_64_muen/virtualbox-hwaccl.mk
@@ -1,11 +1,16 @@
 include $(REP_DIR)/lib/mk/virtualbox-common.inc
 
+LIBS  += stdcxx
+
 SRC_CC = pgm.cc sup.cc
 
 INC_DIR += $(call select_from_repositories,src/lib/libc)
 
+INC_DIR += $(VBOX_DIR)/Main/xml
+INC_DIR += $(VBOX_DIR)/Main/include
 INC_DIR += $(VBOX_DIR)/VMM/include
 INC_DIR += $(REP_DIR)/src/virtualbox
+INC_DIR += $(REP_DIR)/src/virtualbox/frontend
 INC_DIR += $(REP_DIR)/src/virtualbox/spec/muen
 
 vpath pgm.cc $(REP_DIR)/src/virtualbox/
diff --git a/repos/ports/lib/mk/spec/nova/virtualbox-hwaccl.mk b/repos/ports/lib/mk/spec/nova/virtualbox-hwaccl.mk
index c5e53ecf98..a924bc8f7e 100644
--- a/repos/ports/lib/mk/spec/nova/virtualbox-hwaccl.mk
+++ b/repos/ports/lib/mk/spec/nova/virtualbox-hwaccl.mk
@@ -1,12 +1,17 @@
 include $(REP_DIR)/lib/mk/virtualbox-common.inc
 
+LIBS  += stdcxx
+
 SRC_CC = sup.cc pgm.cc
 
 INC_DIR += $(call select_from_repositories,src/lib/libc)
 INC_DIR += $(call select_from_repositories,src/lib/pthread)
 
+INC_DIR += $(VBOX_DIR)/Main/xml
+INC_DIR += $(VBOX_DIR)/Main/include
 INC_DIR += $(VBOX_DIR)/VMM/include
 INC_DIR += $(REP_DIR)/src/virtualbox
+INC_DIR += $(REP_DIR)/src/virtualbox/frontend
 INC_DIR += $(REP_DIR)/src/virtualbox/spec/nova
 
 vpath pgm.cc $(REP_DIR)/src/virtualbox/
diff --git a/repos/ports/lib/mk/virtualbox-hwaccl-off.inc b/repos/ports/lib/mk/virtualbox-hwaccl-off.inc
index de045c126a..58f6beb2e7 100644
--- a/repos/ports/lib/mk/virtualbox-hwaccl-off.inc
+++ b/repos/ports/lib/mk/virtualbox-hwaccl-off.inc
@@ -1,10 +1,15 @@
 include $(REP_DIR)/lib/mk/virtualbox-common.inc
 
+LIBS  += stdcxx
+
 SRC_CC = pgm.cc sup.cc
 
 INC_DIR += $(call select_from_repositories,src/lib/libc)
+INC_DIR += $(VBOX_DIR)/Main/xml
+INC_DIR += $(VBOX_DIR)/Main/include
 INC_DIR += $(VBOX_DIR)/VMM/include
 INC_DIR += $(REP_DIR)/src/virtualbox
+INC_DIR += $(REP_DIR)/src/virtualbox/frontend
 INC_DIR += $(REP_DIR)/src/virtualbox/accloff
 
 vpath pgm.cc $(REP_DIR)/src/virtualbox/
diff --git a/repos/ports/lib/mk/virtualbox-main.mk b/repos/ports/lib/mk/virtualbox-main.mk
index eb1a67cd2a..b67f27fd6b 100644
--- a/repos/ports/lib/mk/virtualbox-main.mk
+++ b/repos/ports/lib/mk/virtualbox-main.mk
@@ -67,6 +67,7 @@ SRC_CC += Main/glue/xpcom/helpers.cpp
 
 INC_DIR += $(VBOX_DIR)/Main/xml
 INC_DIR += $(VBOX_DIR)/Main/include
+INC_DIR += $(REP_DIR)/src/virtualbox
 INC_DIR += $(REP_DIR)/src/virtualbox/frontend
 INC_DIR += $(REP_DIR)/src/virtualbox/frontend/VBoxAPIWrap
 
diff --git a/repos/ports/src/virtualbox/accloff/sup.cc b/repos/ports/src/virtualbox/accloff/sup.cc
index 550cef8a20..1582ba3206 100644
--- a/repos/ports/src/virtualbox/accloff/sup.cc
+++ b/repos/ports/src/virtualbox/accloff/sup.cc
@@ -123,6 +123,9 @@ void genode_update_tsc(void (*update_func)(void), unsigned long update_us)
 }
 
 
+HRESULT genode_setup_machine(ComObjPtr<Machine> machine) { return S_OK; }
+
+
 bool Vmm_memory::revoke_from_vm(Mem_region *r)
 {
 	PWRN("%s unimplemented", __func__);
diff --git a/repos/ports/src/virtualbox/frontend/main.cc b/repos/ports/src/virtualbox/frontend/main.cc
index bdef5a9710..2b54fa33f8 100644
--- a/repos/ports/src/virtualbox/frontend/main.cc
+++ b/repos/ports/src/virtualbox/frontend/main.cc
@@ -34,6 +34,7 @@
 /* Genode port specific includes */
 #include "console.h"
 #include "fb.h"
+#include "../sup.h"
 
 static char c_vbox_file[128];
 static char c_vbox_vmname[128];
@@ -106,6 +107,10 @@ HRESULT setupmachine()
 	if (FAILED(rc))
 		return rc;
 
+	rc = genode_setup_machine(machine);
+	if (FAILED(rc))
+		return rc;
+
 	rc = virtualbox->RegisterMachine(machine);
 	if (FAILED(rc))
 		return rc;
diff --git a/repos/ports/src/virtualbox/spec/muen/sup.cc b/repos/ports/src/virtualbox/spec/muen/sup.cc
index 416b980985..378939ec82 100644
--- a/repos/ports/src/virtualbox/spec/muen/sup.cc
+++ b/repos/ports/src/virtualbox/spec/muen/sup.cc
@@ -747,6 +747,25 @@ uint64_t genode_cpu_hz()
 }
 
 
+HRESULT genode_setup_machine(ComObjPtr<Machine> machine)
+{
+	HRESULT rc;
+	ULONG cCpus;
+	rc = machine->COMGETTER(CPUCount)(&cCpus);
+	if (FAILED(rc))
+		return rc;
+
+	if (cCpus != 1) {
+		PWRN("Configured CPUs %u not supported, reducing to 1.", cCpus);
+		rc = machine->COMSETTER(CPUCount)(1);
+		if (FAILED(rc))
+			return rc;
+	}
+
+	return S_OK;
+}
+
+
 /**
  * Dummies and unimplemented stuff.
  */
diff --git a/repos/ports/src/virtualbox/spec/nova/sup.cc b/repos/ports/src/virtualbox/spec/nova/sup.cc
index 8f832ccf8d..e46b8833cd 100644
--- a/repos/ports/src/virtualbox/spec/nova/sup.cc
+++ b/repos/ports/src/virtualbox/spec/nova/sup.cc
@@ -216,6 +216,9 @@ void genode_update_tsc(void (*update_func)(void), unsigned long update_us)
 }
 
 
+HRESULT genode_setup_machine(ComObjPtr<Machine> machine) { return S_OK; }
+
+
 bool Vmm_memory::revoke_from_vm(Mem_region *r)
 {
 	Assert(r);
diff --git a/repos/ports/src/virtualbox/sup.h b/repos/ports/src/virtualbox/sup.h
index b2029feeee..c0c68b8916 100644
--- a/repos/ports/src/virtualbox/sup.h
+++ b/repos/ports/src/virtualbox/sup.h
@@ -20,8 +20,11 @@
 /* VirtualBox includes */
 #include <VBox/vmm/vm.h>
 #include <VBox/vmm/gvmm.h>
+#include <VBox/com/ptr.h>
 #include <iprt/param.h>
 
+#include "MachineImpl.h"
+
 /**
  * Returns true if a vCPU could be started. If false we run without
  * hardware acceleration support.
@@ -42,4 +45,6 @@ Genode::Cpu_session * get_vcpu_cpu_session();
 void genode_VMMR0_DO_GVMM_CREATE_VM(PSUPVMMR0REQHDR pReqHdr);
 void genode_VMMR0_DO_GVMM_REGISTER_VMCPU(PVMR0 pVMR0, VMCPUID idCpu);
 
+HRESULT genode_setup_machine(ComObjPtr<Machine> machine);
+
 #endif /* _SUP_H_ */