diff --git a/chapter2/Bitcoin_payment/package-lock.json b/chapter2/Bitcoin_payment/package-lock.json
index e198a2d..5061034 100644
--- a/chapter2/Bitcoin_payment/package-lock.json
+++ b/chapter2/Bitcoin_payment/package-lock.json
@@ -1135,9 +1135,9 @@
       }
     },
     "underscore": {
-      "version": "1.9.1",
-      "resolved": "https://registry.npmjs.org/underscore/-/underscore-1.9.1.tgz",
-      "integrity": "sha512-5/4etnCkd9c8gwgowi5/om/mYO5ajCaOgdzj/oW+0eQV9WxKBDZw5+ycmKmeaTXjInS/W0BzpGLo2xR2aBwZdg=="
+      "version": "1.12.1",
+      "resolved": "https://registry.npmjs.org/underscore/-/underscore-1.12.1.tgz",
+      "integrity": "sha512-hEQt0+ZLDVUMhebKxL4x1BTtDY7bavVofhZ9KZ4aI26X9SRaE+Y3m83XUL1UP2jn8ynjndwCCpEHdUG+9pP1Tw=="
     },
     "unpipe": {
       "version": "1.0.0",
diff --git a/chapter2/Bitcoin_payment/package.json b/chapter2/Bitcoin_payment/package.json
index d7fa3db..ecf74bb 100644
--- a/chapter2/Bitcoin_payment/package.json
+++ b/chapter2/Bitcoin_payment/package.json
@@ -11,6 +11,6 @@
     "express": "^4.16.3",
     "request": "^2.88.0",
     "request-promise": "^4.2.2",
-    "underscore": "^1.9.1"
+    "underscore": "^1.12.1"
   }
 }