diff --git a/src/syscall.cpp b/src/syscall.cpp
index 838bfee..5619293 100644
--- a/src/syscall.cpp
+++ b/src/syscall.cpp
@@ -1205,7 +1205,7 @@ void Ec::sys_assign_gsi()
         sys_finish<Sys_regs::BAD_DEV>();
     }
 
-    if (EXPECT_FALSE (!Gsi::gsi_table[gsi].ioapic && (!Pd::current->Space_mem::lookup (r->dev(), phys) || ((rid = Pci::phys_to_rid (phys)) == ~0U && (rid = Hpet::phys_to_rid (phys)) == ~0U)))) {
+    if (EXPECT_FALSE (!Gsi::gsi_table[gsi].ioapic && r->dev() && (!Pd::current->Space_mem::lookup (r->dev(), phys) || ((rid = Pci::phys_to_rid (phys)) == ~0U && (rid = Hpet::phys_to_rid (phys)) == ~0U)))) {
         trace (TRACE_ERROR, "%s: Non-DEV CAP (%#lx)", __func__, r->dev());
         sys_finish<Sys_regs::BAD_DEV>();
     }