diff --git a/package.json b/package.json
index a66e455..3231c14 100644
--- a/package.json
+++ b/package.json
@@ -22,7 +22,7 @@
     "koa-ctx-cache-control": "^1.0.0",
     "koa-proxy": "^0.8.0",
     "koa-router": "^7.0.1",
-    "lodash": "^4.17.1",
+    "lodash": "^4.17.21",
     "mapnik": "^3.7.1",
     "morgan": "^1.7.0",
     "ngeohash": "^0.6.0",
diff --git a/yarn.lock b/yarn.lock
index 1a7d519..2eafb3c 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -982,7 +982,7 @@ compressible@^2.0.0, compressible@~2.0.13:
 
 compression@^1.5.0:
   version "1.7.2"
-  resolved "http://registry.npmjs.org/compression/-/compression-1.7.2.tgz#aaffbcd6aaf854b44ebb280353d5ad1651f59a69"
+  resolved "https://registry.npmjs.org/compression/-/compression-1.7.2.tgz#aaffbcd6aaf854b44ebb280353d5ad1651f59a69"
   dependencies:
     accepts "~1.3.4"
     bytes "3.0.0"
@@ -1505,7 +1505,7 @@ event-emitter@~0.3.5:
 
 event-stream@~3.3.0:
   version "3.3.4"
-  resolved "http://registry.npmjs.org/event-stream/-/event-stream-3.3.4.tgz#4ab4c9a0f5a54db9338b4c34d86bfce8f4b35571"
+  resolved "https://registry.npmjs.org/event-stream/-/event-stream-3.3.4.tgz#4ab4c9a0f5a54db9338b4c34d86bfce8f4b35571"
   dependencies:
     duplexer "~0.1.1"
     from "~0"
@@ -2998,9 +2998,9 @@ lodash.toarray@^4.4.0:
   version "4.4.0"
   resolved "https://registry.yarnpkg.com/lodash.toarray/-/lodash.toarray-4.4.0.tgz#24c4bfcd6b2fba38bfd0594db1179d8e9b656561"
 
-lodash@^4.0.0, lodash@^4.12.0, lodash@^4.13.1, lodash@^4.14.0, lodash@^4.17.1, lodash@^4.17.4, lodash@^4.3.0:
-  version "4.17.5"
-  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.5.tgz#99a92d65c0272debe8c96b6057bc8fbfa3bed511"
+lodash@^4.0.0, lodash@^4.12.0, lodash@^4.13.1, lodash@^4.14.0, lodash@^4.17.21, lodash@^4.17.4, lodash@^4.3.0:
+  version "4.17.21"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.21.tgz#679591c564c3bffaae8454cf0b3df370c3d6911c"
 
 longest@^1.0.1:
   version "1.0.1"
@@ -3396,7 +3396,7 @@ once@^1.3.0, once@^1.3.3, once@^1.4.0:
 
 onetime@^1.0.0:
   version "1.1.0"
-  resolved "http://registry.npmjs.org/onetime/-/onetime-1.1.0.tgz#a1f7838f8314c516f05ecefcbc4ccfe04b4ed789"
+  resolved "https://registry.npmjs.org/onetime/-/onetime-1.1.0.tgz#a1f7838f8314c516f05ecefcbc4ccfe04b4ed789"
 
 only@0.0.2:
   version "0.0.2"