diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c
index a3bb5aa221..5841dfc4fe 100644
--- a/hw/s390x/s390-pci-inst.c
+++ b/hw/s390x/s390-pci-inst.c
@@ -396,7 +396,7 @@ static MemoryRegion *s390_get_subregion(MemoryRegion *mr, uint64_t offset,
     uint64_t subregion_size;
 
     QTAILQ_FOREACH(subregion, &mr->subregions, subregions_link) {
-        subregion_size = int128_get64(subregion->size);
+        subregion_size = memory_region_size(subregion);
         if ((offset >= subregion->addr) &&
             (offset + len) <= (subregion->addr + subregion_size)) {
             mr = subregion;