diff --git a/package-lock.json b/package-lock.json
index 985448a..7301faa 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -199,7 +199,8 @@
     "file-uri-to-path": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/file-uri-to-path/-/file-uri-to-path-1.0.0.tgz",
-      "integrity": "sha512-0Zt+s3L7Vf1biwWZ29aARiVYLx7iMGnEUl9x33fbB/j3jR81u/O2LbqK+Bm1CDSNDKVtJ/YjwY7TUd5SkeLQLw=="
+      "integrity": "sha512-0Zt+s3L7Vf1biwWZ29aARiVYLx7iMGnEUl9x33fbB/j3jR81u/O2LbqK+Bm1CDSNDKVtJ/YjwY7TUd5SkeLQLw==",
+      "optional": true
     },
     "find-up": {
       "version": "1.1.2",
@@ -351,9 +352,9 @@
       }
     },
     "lodash": {
-      "version": "3.10.1",
-      "resolved": "https://registry.npmjs.org/lodash/-/lodash-3.10.1.tgz",
-      "integrity": "sha1-W/Rejkm6QYnhfUgnid/RW9FAt7Y="
+      "version": "4.17.21",
+      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.21.tgz",
+      "integrity": "sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg=="
     },
     "lodash.assign": {
       "version": "4.2.0",
diff --git a/package.json b/package.json
index d114708..c3c8bb0 100644
--- a/package.json
+++ b/package.json
@@ -19,7 +19,7 @@
   "dependencies": {
     "bemuse-notechart": "^45.1.0",
     "bluebird": "^3.3.3",
-    "lodash": "^3.10.1",
+    "lodash": "^4.17.21",
     "minimist": "^1.2.0",
     "semver": "^5.1.0",
     "yargs": "^4.2.0"