diff --git a/package-lock.json b/package-lock.json
new file mode 100644
index 0000000..0a6a478
--- /dev/null
+++ b/package-lock.json
@@ -0,0 +1,191 @@
+{
+  "name": "@signalk/nmea0183-utilities",
+  "version": "0.6.0",
+  "lockfileVersion": 1,
+  "requires": true,
+  "dependencies": {
+    "assertion-error": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/assertion-error/-/assertion-error-1.0.0.tgz",
+      "integrity": "sha1-x/hUOP3UZrx8oWq5DIFRN5el0js=",
+      "dev": true
+    },
+    "chai": {
+      "version": "2.1.2",
+      "resolved": "https://registry.npmjs.org/chai/-/chai-2.1.2.tgz",
+      "integrity": "sha1-AefKyJUM41bVIK/ngTJQWxzVRA8=",
+      "dev": true,
+      "requires": {
+        "assertion-error": "1.0.0",
+        "deep-eql": "0.1.3"
+      }
+    },
+    "chai-things": {
+      "version": "0.2.0",
+      "resolved": "https://registry.npmjs.org/chai-things/-/chai-things-0.2.0.tgz",
+      "integrity": "sha1-xVEoN4+bs5nplPAAUhUZhO1uvnA=",
+      "dev": true
+    },
+    "commander": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/commander/-/commander-2.3.0.tgz",
+      "integrity": "sha1-/UMOiJgy7DU7ms0d4hfBHLPu+HM=",
+      "dev": true
+    },
+    "debug": {
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/debug/-/debug-2.2.0.tgz",
+      "integrity": "sha1-+HBX6ZWxofauaklgZkE3vFbwOdo=",
+      "dev": true,
+      "requires": {
+        "ms": "0.7.1"
+      }
+    },
+    "deep-eql": {
+      "version": "0.1.3",
+      "resolved": "https://registry.npmjs.org/deep-eql/-/deep-eql-0.1.3.tgz",
+      "integrity": "sha1-71WKyrjeJSBs1xOQbXTlaTDrafI=",
+      "dev": true,
+      "requires": {
+        "type-detect": "0.1.1"
+      }
+    },
+    "diff": {
+      "version": "1.4.0",
+      "resolved": "https://registry.npmjs.org/diff/-/diff-1.4.0.tgz",
+      "integrity": "sha1-fyjS657nsVqX79ic5j3P2qPMur8=",
+      "dev": true
+    },
+    "escape-string-regexp": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/escape-string-regexp/-/escape-string-regexp-1.0.2.tgz",
+      "integrity": "sha1-Tbwv5nTnGUnK8/smlc5/LcHZqNE=",
+      "dev": true
+    },
+    "glob": {
+      "version": "3.2.11",
+      "resolved": "https://registry.npmjs.org/glob/-/glob-3.2.11.tgz",
+      "integrity": "sha1-Spc/Y1uRkPcV0QmH1cAP0oFevj0=",
+      "dev": true,
+      "requires": {
+        "inherits": "2.0.3",
+        "minimatch": "0.3.0"
+      }
+    },
+    "growl": {
+      "version": "1.9.2",
+      "resolved": "https://registry.npmjs.org/growl/-/growl-1.9.2.tgz",
+      "integrity": "sha1-Dqd0NxXbjY3ixe3hd14bRayFwC8=",
+      "dev": true
+    },
+    "inherits": {
+      "version": "2.0.3",
+      "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.3.tgz",
+      "integrity": "sha1-Yzwsg+PaQqUC9SRmAiSA9CCCYd4=",
+      "dev": true
+    },
+    "jade": {
+      "version": "0.26.3",
+      "resolved": "https://registry.npmjs.org/jade/-/jade-0.26.3.tgz",
+      "integrity": "sha1-jxDXl32NefL2/4YqgbBRPMslaGw=",
+      "dev": true,
+      "requires": {
+        "commander": "0.6.1",
+        "mkdirp": "0.3.0"
+      },
+      "dependencies": {
+        "commander": {
+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/commander/-/commander-0.6.1.tgz",
+          "integrity": "sha1-+mihT2qUXVTbvlDYzbMyDp47GgY=",
+          "dev": true
+        },
+        "mkdirp": {
+          "version": "0.3.0",
+          "resolved": "https://registry.npmjs.org/mkdirp/-/mkdirp-0.3.0.tgz",
+          "integrity": "sha1-G79asbqCevI1dRQ0kEJkVfSB/h4=",
+          "dev": true
+        }
+      }
+    },
+    "lru-cache": {
+      "version": "2.7.3",
+      "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-2.7.3.tgz",
+      "integrity": "sha1-bUUk6LlV+V1PW1iFHOId1y+06VI=",
+      "dev": true
+    },
+    "minimatch": {
+      "version": "0.3.0",
+      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-0.3.0.tgz",
+      "integrity": "sha1-J12O2qxPG7MyZHIInnlJyDlGmd0=",
+      "dev": true,
+      "requires": {
+        "lru-cache": "2.7.3",
+        "sigmund": "1.0.1"
+      }
+    },
+    "minimist": {
+      "version": "0.0.8",
+      "resolved": "https://registry.npmjs.org/minimist/-/minimist-0.0.8.tgz",
+      "integrity": "sha1-hX/Kv8M5fSYluCKCYuhqp6ARsF0=",
+      "dev": true
+    },
+    "mkdirp": {
+      "version": "0.5.1",
+      "resolved": "https://registry.npmjs.org/mkdirp/-/mkdirp-0.5.1.tgz",
+      "integrity": "sha1-MAV0OOrGz3+MR2fzhkjWaX11yQM=",
+      "dev": true,
+      "requires": {
+        "minimist": "0.0.8"
+      }
+    },
+    "mocha": {
+      "version": "2.5.3",
+      "resolved": "https://registry.npmjs.org/mocha/-/mocha-2.5.3.tgz",
+      "integrity": "sha1-FhvlvetJZ3HrmzV0UFC2IrWu/Fg=",
+      "dev": true,
+      "requires": {
+        "commander": "2.3.0",
+        "debug": "2.2.0",
+        "diff": "1.4.0",
+        "escape-string-regexp": "1.0.2",
+        "glob": "3.2.11",
+        "growl": "1.9.2",
+        "jade": "0.26.3",
+        "mkdirp": "0.5.1",
+        "supports-color": "1.2.0",
+        "to-iso-string": "0.0.2"
+      }
+    },
+    "ms": {
+      "version": "0.7.1",
+      "resolved": "https://registry.npmjs.org/ms/-/ms-0.7.1.tgz",
+      "integrity": "sha1-nNE8A62/8ltl7/3nzoZO6VIBcJg=",
+      "dev": true
+    },
+    "sigmund": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/sigmund/-/sigmund-1.0.1.tgz",
+      "integrity": "sha1-P/IfGYytIXX587eBhT/ZTQ0ZtZA=",
+      "dev": true
+    },
+    "supports-color": {
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-1.2.0.tgz",
+      "integrity": "sha1-/x7R5hFp0Gs88tWI4YixjYhH4X4=",
+      "dev": true
+    },
+    "to-iso-string": {
+      "version": "0.0.2",
+      "resolved": "https://registry.npmjs.org/to-iso-string/-/to-iso-string-0.0.2.tgz",
+      "integrity": "sha1-TcGeZk38y+Jb2NtQiwDG2hWCVdE=",
+      "dev": true
+    },
+    "type-detect": {
+      "version": "0.1.1",
+      "resolved": "https://registry.npmjs.org/type-detect/-/type-detect-0.1.1.tgz",
+      "integrity": "sha1-C6XsKohWQORw6k6FBZcZANrFiCI=",
+      "dev": true
+    }
+  }
+}
diff --git a/package.json b/package.json
index a8cf069..cc748d8 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@signalk/nmea0183-utilities",
-  "version": "0.5.0",
+  "version": "0.6.0",
   "description": "Various utilities for transforming NMEA0183 units into SI units for use in SK.",
   "main": "index.js",
   "scripts": {