diff --git a/lib/update-v8/constants.js b/lib/update-v8/constants.js
index b4daef2e..86d601d6 100644
--- a/lib/update-v8/constants.js
+++ b/lib/update-v8/constants.js
@@ -44,6 +44,9 @@ const fastFloatReplace = `/third_party/fast_float/src/*
 const highwayIgnore = `/third_party/highway/src/*
 !/third_party/highway/src/hwy`;
 
+const dragonboxIgnore = `/third_party/dragonbox/src/*
+!/third_party/dragonbox/src/include`;
+
 export const v8Deps = [
   {
     name: 'trace_event',
@@ -133,5 +136,14 @@ export const v8Deps = [
     repo: 'third_party/simdutf',
     gitignore: '!/third_party/simdutf',
     since: 134
-  }
+  },
+  {
+    name: 'dragonbox',
+    repo: 'third_party/dragonbox/src',
+    gitignore: {
+      match: '/third_party/dragonbox/src',
+      replace: dragonboxIgnore
+    },
+    since: 138
+  },
 ];