diff --git a/configure.py b/configure.py
index 62f041ce52b..8be9e9ca5c4 100755
--- a/configure.py
+++ b/configure.py
@@ -1498,6 +1498,7 @@ def configure_v8(o):
   o['variables']['v8_enable_pointer_compression'] = 1 if options.enable_pointer_compression else 0
   o['variables']['v8_enable_31bit_smis_on_64bit_arch'] = 1 if options.enable_pointer_compression else 0
   o['variables']['v8_enable_shared_ro_heap'] = 0 if options.enable_pointer_compression or options.disable_shared_ro_heap else 1
+  o['variables']['v8_enable_extensible_ro_snapshot'] = 0
   o['variables']['v8_trace_maps'] = 1 if options.trace_maps else 0
   o['variables']['node_use_v8_platform'] = b(not options.without_v8_platform)
   o['variables']['node_use_bundled_v8'] = b(not options.without_bundled_v8)
diff --git a/tools/v8_gypfiles/features.gypi b/tools/v8_gypfiles/features.gypi
index 3a7f355ef80..aa946a27741 100644
--- a/tools/v8_gypfiles/features.gypi
+++ b/tools/v8_gypfiles/features.gypi
@@ -280,6 +280,10 @@
     # Sets -DV8_USE_ZLIB
     'v8_use_zlib%': 1,
 
+    # Whether custom embedder snapshots may extend (= allocate new objects in)
+    # ReadOnlySpace.
+    'v8_enable_extensible_ro_snapshot%': 1,
+
     # Variables from v8.gni
 
     # Enable ECMAScript Internationalization API. Enabling this feature will
@@ -460,6 +464,9 @@
       ['v8_use_zlib==1', {
         'defines': ['V8_USE_ZLIB',],
       }],
+      ['v8_enable_extensible_ro_snapshot==1', {
+        'defines': ['V8_ENABLE_EXTENSIBLE_RO_SNAPSHOT',],
+      }],
       ['v8_enable_precise_zone_stats==1', {
         'defines': ['V8_ENABLE_PRECISE_ZONE_STATS',],
       }],