diff --git a/package-lock.json b/package-lock.json
index c2bf6e2..a1b7cb9 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -222,6 +222,15 @@
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       "dev": true
     },
+    "copy-anything": {
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+      "resolved": "https://registry.npmjs.org/copy-anything/-/copy-anything-2.0.1.tgz",
+      "integrity": "sha512-lA57e7viQHOdPQcrytv5jFeudZZOXuyk47lZym279FiDQ8jeZomXiGuVf6ffMKkJ+3TIai3J1J3yi6M+/4U35g==",
+      "dev": true,
+      "requires": {
+        "is-what": "^3.7.1"
+      }
+    },
     "core-util-is": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/core-util-is/-/core-util-is-1.0.2.tgz",
@@ -602,6 +611,12 @@
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       "optional": true
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+    "is-what": {
+      "version": "3.12.0",
+      "resolved": "https://registry.npmjs.org/is-what/-/is-what-3.12.0.tgz",
+      "integrity": "sha512-2ilQz5/f/o9V7WRWJQmpFYNmQFZ9iM+OXRonZKcYgTkCzjb949Vi4h282PD1UfmgHk666rcWonbRJ++KI41VGw==",
+      "dev": true
+    },
     "is-wsl": {
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       "resolved": "https://registry.npmjs.org/is-wsl/-/is-wsl-1.1.0.tgz",
@@ -691,12 +706,48 @@
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-      "version": "1.3.3",
-      "resolved": "https://registry.npmjs.org/less/-/less-1.3.3.tgz",
-      "integrity": "sha1-fujzAKQQgPNUTIDHpwzfamEoDPk=",
+      "version": "4.1.0",
+      "resolved": "https://registry.npmjs.org/less/-/less-4.1.0.tgz",
+      "integrity": "sha512-w1Ag/f34g7LwtQ/sMVSGWIyZx+gG9ZOAEtyxeX1fG75is6BMyC2lD5kG+1RueX7PkAvlQBm2Lf2aN2j0JbVr2A==",
+      "dev": true,
+      "requires": {
+        "copy-anything": "^2.0.1",
+        "errno": "^0.1.1",
+        "graceful-fs": "^4.1.2",
+        "image-size": "~0.5.0",
+        "make-dir": "^2.1.0",
+        "mime": "^1.4.1",
+        "needle": "^2.5.2",
+        "parse-node-version": "^1.0.1",
+        "source-map": "~0.6.0",
+        "tslib": "^1.10.0"
+      },
+      "dependencies": {
+        "mime": {
+          "version": "1.6.0",
+          "resolved": "https://registry.npmjs.org/mime/-/mime-1.6.0.tgz",
+          "integrity": "sha512-x0Vn8spI+wuJ1O6S7gnbaQg8Pxh4NNHb7KSINmEWKiPE4RKOplvijn+NkmYmmRgP68mc70j2EbeTFRsrswaQeg==",
+          "dev": true,
+          "optional": true
+        },
+        "source-map": {
+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true,
+          "optional": true
+        }
+      }
+    },
+    "make-dir": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/make-dir/-/make-dir-2.1.0.tgz",
+      "integrity": "sha512-LS9X+dc8KLxXCb8dni79fLIIUA5VyZoyjSMCwTluaXA0o27cCK0bhXkpgw+sTXVpPy/lSO57ilRixqk0vDmtRA==",
       "dev": true,
+      "optional": true,
       "requires": {
-        "ycssmin": ">=1.0.1"
+        "pify": "^4.0.1",
+        "semver": "^5.6.0"
       }
     },
     "media-typer": {
@@ -761,6 +812,37 @@
       "integrity": "sha1-VgiurfwAvmwpAd9fmGF4jeDVl8g=",
       "dev": true
     },
+    "needle": {
+      "version": "2.6.0",
+      "resolved": "https://registry.npmjs.org/needle/-/needle-2.6.0.tgz",
+      "integrity": "sha512-KKYdza4heMsEfSWD7VPUIz3zX2XDwOyX2d+geb4vrERZMT5RMU6ujjaD+I5Yr54uZxQ2w6XRTAhHBbSCyovZBg==",
+      "dev": true,
+      "optional": true,
+      "requires": {
+        "debug": "^3.2.6",
+        "iconv-lite": "^0.4.4",
+        "sax": "^1.2.4"
+      },
+      "dependencies": {
+        "debug": {
+          "version": "3.2.7",
+          "resolved": "https://registry.npmjs.org/debug/-/debug-3.2.7.tgz",
+          "integrity": "sha512-CFjzYYAi4ThfiQvizrFQevTTXHtnCqWfe7x1AhgEscTz6ZbLbfoLRLPugTQyBth6f8ZERVUSyWHFD/7Wu4t1XQ==",
+          "dev": true,
+          "optional": true,
+          "requires": {
+            "ms": "^2.1.1"
+          }
+        },
+        "ms": {
+          "version": "2.1.3",
+          "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.3.tgz",
+          "integrity": "sha512-6FlzubTLZG3J2a/NVCAleEhjzq5oxgHyaCU9yYXvcLsvoVaHJq/s5xXI6/XXP6tz7R9xAOtHnSO/tXtF3WRTlA==",
+          "dev": true,
+          "optional": true
+        }
+      }
+    },
     "negotiator": {
       "version": "0.6.1",
       "resolved": "https://registry.npmjs.org/negotiator/-/negotiator-0.6.1.tgz",
@@ -792,6 +874,12 @@
         "is-wsl": "^1.1.0"
       }
     },
+    "parse-node-version": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/parse-node-version/-/parse-node-version-1.0.1.tgz",
+      "integrity": "sha512-3YHlOa/JgH6Mnpr05jP9eDG254US9ek25LyIxZlDItp2iJtwyaXQb57lBYLdT3MowkUFYEV2XXNAYIPlESvJlA==",
+      "dev": true
+    },
     "parseurl": {
       "version": "1.3.2",
       "resolved": "https://registry.npmjs.org/parseurl/-/parseurl-1.3.2.tgz",
@@ -811,6 +899,13 @@
       "dev": true,
       "optional": true
     },
+    "pify": {
+      "version": "4.0.1",
+      "resolved": "https://registry.npmjs.org/pify/-/pify-4.0.1.tgz",
+      "integrity": "sha512-uB80kBFb/tfd68bVleG9T5GGsGPjJrLAUpR5PZIrhBnIaRTQRjqdJSsIKkOP6OAIFbj7GOrcudc5pNjZ+geV2g==",
+      "dev": true,
+      "optional": true
+    },
     "promise": {
       "version": "7.3.1",
       "resolved": "https://registry.npmjs.org/promise/-/promise-7.3.1.tgz",
@@ -928,6 +1023,20 @@
       "integrity": "sha1-iTMSr2myEj3vcfV4iQAWce6yyFM=",
       "dev": true
     },
+    "sax": {
+      "version": "1.2.4",
+      "resolved": "https://registry.npmjs.org/sax/-/sax-1.2.4.tgz",
+      "integrity": "sha512-NqVDv9TpANUjFm0N8uM5GxL36UgKi9/atZw+x7YFnQ8ckwFGKrl4xX4yWtrey3UJm5nP1kUbnYgLopqWNSRhWw==",
+      "dev": true,
+      "optional": true
+    },
+    "semver": {
+      "version": "5.7.1",
+      "resolved": "https://registry.npmjs.org/semver/-/semver-5.7.1.tgz",
+      "integrity": "sha512-sauaDf/PZdVgrLTNYHRtpXa1iRiKcaebiKQ1BJdpQlWH2lCvexQdX55snPFyK7QzpudqbCI0qXFfOasHdyNDGQ==",
+      "dev": true,
+      "optional": true
+    },
     "send": {
       "version": "0.16.1",
       "resolved": "https://registry.npmjs.org/send/-/send-0.16.1.tgz",
@@ -1063,6 +1172,12 @@
       "integrity": "sha1-cXuPIgzAu3tE5AUUwisui7xw2Lk=",
       "dev": true
     },
+    "tslib": {
+      "version": "1.14.1",
+      "resolved": "https://registry.npmjs.org/tslib/-/tslib-1.14.1.tgz",
+      "integrity": "sha512-Xni35NKzjgMrwevysHTCArtLDpPvye8zV/0E4EyYn43P7/7qvQwPh9BGkHewbMulVntbigmcT7rdX3BNo9wRJg==",
+      "dev": true
+    },
     "tunnel-agent": {
       "version": "0.6.0",
       "resolved": "https://registry.npmjs.org/tunnel-agent/-/tunnel-agent-0.6.0.tgz",
@@ -1153,13 +1268,6 @@
           "optional": true
         }
       }
-    },
-    "ycssmin": {
-      "version": "1.0.1",
-      "resolved": "https://registry.npmjs.org/ycssmin/-/ycssmin-1.0.1.tgz",
-      "integrity": "sha1-fN3o23jPqwDSkBw7IwHjBPr03xY=",
-      "dev": true,
-      "optional": true
     }
   }
 }
diff --git a/package.json b/package.json
index 9a46f9a..48e5e9d 100644
--- a/package.json
+++ b/package.json
@@ -38,7 +38,7 @@
     "express-less": "^0.1.0",
     "fs-extra": ">= 0.0.4",
     "jsmin": "^1.0.1",
-    "less": "1.3.x",
+    "less": "4.1.x",
     "mime": "1.2.x",
     "opn": "^5.1.0",
     "qunit": "0.4.x",