diff --git a/package-lock.json b/package-lock.json
new file mode 100644
index 0000000..e8efdf2
--- /dev/null
+++ b/package-lock.json
@@ -0,0 +1,26 @@
+{
+	"name": "robot-js",
+	"version": "1.0.2",
+	"lockfileVersion": 1,
+	"requires": true,
+	"dependencies": {
+		"node-png": {
+			"version": "0.4.3",
+			"resolved": "https://registry.npmjs.org/node-png/-/node-png-0.4.3.tgz",
+			"integrity": "sha1-RQIjeWuC08yg/+Sl1cf6l0hZdOc=",
+			"dev": true
+		},
+		"readline-sync": {
+			"version": "1.4.7",
+			"resolved": "https://registry.npmjs.org/readline-sync/-/readline-sync-1.4.7.tgz",
+			"integrity": "sha1-ABv91MBhEMPAhMY798alYCIhPzA=",
+			"dev": true
+		},
+		"sprintf-js": {
+			"version": "1.1.1",
+			"resolved": "https://registry.npmjs.org/sprintf-js/-/sprintf-js-1.1.1.tgz",
+			"integrity": "sha1-Nr54Mgr+WAH2zqPueLblqrlA6gw=",
+			"dev": true
+		}
+	}
+}
diff --git a/package.json b/package.json
index 5e4e0bb..c571722 100644
--- a/package.json
+++ b/package.json
@@ -60,9 +60,9 @@
 
 	"devDependencies":
 	{
-		"sprintf-js"	: "^1",
-		"node-png"		: "^0",
-		"readline-sync"	: "^1"
+		"sprintf-js"	: "~1.1",
+		"node-png"		: "~0.4",
+		"readline-sync"	: "~1.4"
 	},
 
 	"scripts":
diff --git a/yarn.lock b/yarn.lock
new file mode 100644
index 0000000..ab5552d
--- /dev/null
+++ b/yarn.lock
@@ -0,0 +1,15 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
+node-png@~0.4:
+  version "0.4.3"
+  resolved "https://registry.yarnpkg.com/node-png/-/node-png-0.4.3.tgz#450223796b82d3cca0ffe4a5d5c7fa97485974e7"
+
+readline-sync@~1.4:
+  version "1.4.7"
+  resolved "https://registry.yarnpkg.com/readline-sync/-/readline-sync-1.4.7.tgz#001bfdd4c06110c3c084c63bf7c6a56022213f30"
+
+sprintf-js@~1.1:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/sprintf-js/-/sprintf-js-1.1.1.tgz#36be78320afe5801f6cea3ee78b6e5aab940ea0c"