diff --git a/exec.c b/exec.c
index 76bfc4a..d00e017 100644
--- a/exec.c
+++ b/exec.c
@@ -341,6 +341,7 @@
                                  hwaddr *plen, bool resolve_subpage)
 {
     MemoryRegionSection *section;
+    MemoryRegion *mr;
     Int128 diff;
 
     section = address_space_lookup_region(d, addr, resolve_subpage);
@@ -350,8 +351,11 @@
     /* Compute offset within MemoryRegion */
     *xlat = addr + section->offset_within_region;
 
-    diff = int128_sub(section->mr->size, int128_make64(addr));
-    *plen = int128_get64(int128_min(diff, int128_make64(*plen)));
+    mr = section->mr;
+    if (memory_region_is_ram(mr)) {
+        diff = int128_sub(mr->size, int128_make64(addr));
+        *plen = int128_get64(int128_min(diff, int128_make64(*plen)));
+    }
     return section;
 }