diff --git a/index.js b/index.js
index 4e79bd1f..8a9acfed 100644
--- a/index.js
+++ b/index.js
@@ -328,40 +328,7 @@ HardSourceWebpackPlugin.prototype.apply = function(compiler) {
   }
 
   var environmentHasher = null;
-  if (typeof options.environmentPaths !== 'undefined') {
-    loggerCore.error(
-      {
-        id: 'environment-paths-deprecated'
-      },
-      'environmentPaths is deprecated, please use environmentHash. ' +
-      'environmentHash accepts the same options.'
-    );
-    if (options.environmentPaths === false) {
-      environmentHasher = function() {
-        return Promise.resolve('');
-      };
-    }
-    else if (typeof options.environmentPaths === 'string') {
-      environmentHasher = function() {
-        return Promise.resolve(options.environmentPaths);
-      };
-    }
-    else {
-      environmentHasher = function() {
-        return envHash(options.environmentPaths);
-      };
-    }
-  }
   if (typeof options.environmentHash !== 'undefined') {
-    if (environmentHasher) {
-      loggerCore.warn(
-        {
-          id: 'environment-paths-and-hash-defined'
-        },
-        'environmentHash is a new option replacing environmentPaths. Please ' +
-        'use only environmentHash.'
-      );
-    }
     if (options.environmentHash === false) {
       environmentHasher = function() {
         return Promise.resolve('');
diff --git a/lib/env-hash.js b/lib/env-hash.js
index ec481781..1fe6df41 100644
--- a/lib/env-hash.js
+++ b/lib/env-hash.js
@@ -48,34 +48,54 @@ function flatten(items) {
 module.exports = function(options) {
   options = options || {};
   var root = options.root || process.cwd();
-  var files = options.files || ['package.json'];
-  var directories = options.directories || ['node_modules'];
+  var files = options.files;
+  var directories = options.directories;
 
-  return Promise.all([
-    hashFiles(root, files),
-    Promise.all(directories.map(function(dir) {
-      return readdir(path.join(root, dir))
-      .then(function(items) {
-        return Promise.all(items.map(function(item) {
-          return stat(path.join(root, dir, item))
-          .then(function(stat) {
-            if (stat.isDirectory()) {
-              return hashFiles(path.join(root, dir, item), files);
-            }
-            if (stat.isFile()) {
-              return hashFile(path.join(root, dir, item))
-              .then(function(hash) {return hash ? [hash] : hash;});
-            }
-          })
-          .catch(function() {console.error(arguments)});
-        }))
-        .then(function(hashes) {return hashes.filter(Boolean);});
-      })
-      .catch(function() {})
-      .then(flatten);
-    }))
-    .then(flatten),
-  ])
+  var hashDefaults = Promise.resolve();
+  if (!files && !directories) {
+    hashDefaults = hashFiles(root, ['package-lock.json', 'yarn.lock']);
+  }
+
+  return hashDefaults
+  .then(function(_defaults) {
+    if (_defaults && _defaults.length > 0) {
+      return [_defaults];
+    }
+    else {
+      if (!files) {
+        files = ['package.json'];
+      }
+      if (!directories) {
+        directories = ['node_modules'];
+      }
+    }
+
+    return Promise.all([
+      hashFiles(root, files),
+      Promise.all(directories.map(function(dir) {
+        return readdir(path.join(root, dir))
+        .then(function(items) {
+          return Promise.all(items.map(function(item) {
+            return stat(path.join(root, dir, item))
+            .then(function(stat) {
+              if (stat.isDirectory()) {
+                return hashFiles(path.join(root, dir, item), files);
+              }
+              if (stat.isFile()) {
+                return hashFile(path.join(root, dir, item))
+                .then(function(hash) {return hash ? [hash] : hash;});
+              }
+            })
+            .catch(function() {console.error(arguments)});
+          }))
+          .then(function(hashes) {return hashes.filter(Boolean);});
+        })
+        .catch(function() {})
+        .then(flatten);
+      }))
+      .then(flatten),
+    ]);
+  })
   .then(flatten)
   .then(function(items) {
     items.forEach(function(item) {
diff --git a/tests/fixtures/hard-source-packageyarnlock-hash/env-hash b/tests/fixtures/hard-source-packageyarnlock-hash/env-hash
new file mode 100644
index 00000000..63d8dbd4
--- /dev/null
+++ b/tests/fixtures/hard-source-packageyarnlock-hash/env-hash
@@ -0,0 +1 @@
+b
\ No newline at end of file
diff --git a/tests/fixtures/hard-source-packageyarnlock-hash/fib/index.js b/tests/fixtures/hard-source-packageyarnlock-hash/fib/index.js
new file mode 100644
index 00000000..bf0205d4
--- /dev/null
+++ b/tests/fixtures/hard-source-packageyarnlock-hash/fib/index.js
@@ -0,0 +1,3 @@
+module.exports = function(n) {
+  return n + (n > 0 ? n - 2 : 0);
+};
\ No newline at end of file
diff --git a/tests/fixtures/hard-source-packageyarnlock-hash/hard-source-config.js b/tests/fixtures/hard-source-packageyarnlock-hash/hard-source-config.js
new file mode 100644
index 00000000..b55d6b3c
--- /dev/null
+++ b/tests/fixtures/hard-source-packageyarnlock-hash/hard-source-config.js
@@ -0,0 +1,7 @@
+{
+  cacheDirectory: "cache",
+  recordsPath: "cache/records.json",
+  environmentHash: {
+    root: __dirname,
+  },
+}
\ No newline at end of file
diff --git a/tests/fixtures/hard-source-packageyarnlock-hash/index.js b/tests/fixtures/hard-source-packageyarnlock-hash/index.js
new file mode 100644
index 00000000..8acf0395
--- /dev/null
+++ b/tests/fixtures/hard-source-packageyarnlock-hash/index.js
@@ -0,0 +1,3 @@
+var fib = require('./fib');
+
+console.log(fib(3));
diff --git a/tests/fixtures/hard-source-packageyarnlock-hash/loader.js b/tests/fixtures/hard-source-packageyarnlock-hash/loader.js
new file mode 100644
index 00000000..693807a3
--- /dev/null
+++ b/tests/fixtures/hard-source-packageyarnlock-hash/loader.js
@@ -0,0 +1,3 @@
+module.exports = function(source) {
+  return require('fs').readFileSync('./vendor/lib1.js') + source;
+};
diff --git a/tests/fixtures/hard-source-packageyarnlock-hash/package-lock.json b/tests/fixtures/hard-source-packageyarnlock-hash/package-lock.json
new file mode 100644
index 00000000..3410062b
--- /dev/null
+++ b/tests/fixtures/hard-source-packageyarnlock-hash/package-lock.json
@@ -0,0 +1 @@
+c
\ No newline at end of file
diff --git a/tests/fixtures/hard-source-packageyarnlock-hash/vendor/lib1.js b/tests/fixtures/hard-source-packageyarnlock-hash/vendor/lib1.js
new file mode 100644
index 00000000..6d012e7f
--- /dev/null
+++ b/tests/fixtures/hard-source-packageyarnlock-hash/vendor/lib1.js
@@ -0,0 +1 @@
+console.log("b");
diff --git a/tests/fixtures/hard-source-packageyarnlock-hash/vendor/lib2.js b/tests/fixtures/hard-source-packageyarnlock-hash/vendor/lib2.js
new file mode 100644
index 00000000..6d012e7f
--- /dev/null
+++ b/tests/fixtures/hard-source-packageyarnlock-hash/vendor/lib2.js
@@ -0,0 +1 @@
+console.log("b");
diff --git a/tests/fixtures/hard-source-packageyarnlock-hash/webpack.config.js b/tests/fixtures/hard-source-packageyarnlock-hash/webpack.config.js
new file mode 100644
index 00000000..3e829a81
--- /dev/null
+++ b/tests/fixtures/hard-source-packageyarnlock-hash/webpack.config.js
@@ -0,0 +1,22 @@
+var fs = require('fs');
+
+var HardSourceWebpackPlugin = require('../../..');
+
+var hardSourceConfig = eval(
+  '(function() { return (' +
+  require('fs')
+  .readFileSync(__dirname + '/hard-source-config.js', 'utf8') +
+  '); })'
+)();
+
+module.exports = {
+  context: __dirname,
+  entry: './loader.js!./index.js',
+  output: {
+    path: __dirname + '/tmp',
+    filename: 'main.js',
+  },
+  plugins: [
+    new HardSourceWebpackPlugin(hardSourceConfig),
+  ],
+};
diff --git a/tests/fixtures/hard-source-packageyarnlock-hash/yarn.lock b/tests/fixtures/hard-source-packageyarnlock-hash/yarn.lock
new file mode 100644
index 00000000..63d8dbd4
--- /dev/null
+++ b/tests/fixtures/hard-source-packageyarnlock-hash/yarn.lock
@@ -0,0 +1 @@
+b
\ No newline at end of file
diff --git a/tests/hard-source.js b/tests/hard-source.js
index f54dc2ad..454d7fff 100644
--- a/tests/hard-source.js
+++ b/tests/hard-source.js
@@ -143,20 +143,6 @@ describe('hard-source features', function() {
     });
   }
 
-  itCompilesEnvironmentHashDisabled('paths-false', [
-    '{',
-    '  cacheDirectory: "cache",',
-    '  recordsPath: "cache/records.json",',
-    '  environmentPaths: false,',
-    '}',
-  ], [
-    '{',
-    '  cacheDirectory: "cache",',
-    '  recordsPath: "cache/records.json",',
-    '  environmentPaths: false,',
-    '}',
-  ]);
-
   itCompilesEnvironmentHashDisabled('false', [
     '{',
     '  cacheDirectory: "cache",',
@@ -171,30 +157,6 @@ describe('hard-source features', function() {
     '}',
   ]);
 
-  itCompilesEnvironmentHash('paths-envhash', [
-    '{',
-    '  cacheDirectory: "cache",',
-    '  recordsPath: "cache/records.json",',
-    '  environmentPaths: {',
-    '    root: __dirname,',
-    '    directories: ["vendor"],',
-    '    files: [],',
-    '  },',
-    '}',
-  ]);
-
-  itCompilesEnvironmentHash('paths-envhash-files', [
-    '{',
-    '  cacheDirectory: "cache",',
-    '  recordsPath: "cache/records.json",',
-    '  environmentPaths: {',
-    '    root: __dirname,',
-    '    directories: ["vendor"],',
-    '    files: ["env-hash"],',
-    '  },',
-    '}',
-  ]);
-
   itCompilesEnvironmentHash('string', [
     '{',
     '  cacheDirectory: "cache",',
@@ -258,4 +220,64 @@ describe('hard-source features', function() {
     '}',
   ]);
 
+  var _packageYarnLockHashConfig = [
+    '{',
+    '  cacheDirectory: "cache",',
+    '  recordsPath: "cache/records.json",',
+    '  environmentHash: {',
+    '    root: __dirname,',
+    '  },',
+    '}',
+  ];
+
+  function itCompilesPackageYarnLockHash(key, files1, files2) {
+    itCompiles('compiles hard-source-packageyarnlock-hash ' + key + ' with fresh cache', 'hard-source-packageyarnlock-hash', function() {
+      return writeFiles('hard-source-packageyarnlock-hash', Object.assign({
+        'hard-source-config.js': _packageYarnLockHashConfig.join('\n'),
+      }, files1));
+    }, function() {
+      return writeFiles('hard-source-packageyarnlock-hash', Object.assign({
+        'hard-source-config.js': _packageYarnLockHashConfig.join('\n'),
+      }, files2))
+      .then(function() {
+        return fs.readFileSync(__dirname + '/fixtures/hard-source-packageyarnlock-hash/tmp/cache/stamp', 'utf8');
+      });
+    }, function(output) {
+      var stamp = fs.readFileSync(__dirname + '/fixtures/hard-source-packageyarnlock-hash/tmp/cache/stamp', 'utf8');
+      expect(stamp).to.not.equal(output.setup2);
+    });
+  }
+
+  itCompilesPackageYarnLockHash('package-lock', {
+    'package-lock.json': 'a',
+    'yarn.lock': null,
+  }, {
+    'package-lock.json': 'b',
+    'yarn.lock': null,
+  });
+
+  itCompilesPackageYarnLockHash('yarn-lock', {
+    'package-lock.json': null,
+    'yarn.lock': 'a',
+  }, {
+    'package-lock.json': null,
+    'yarn.lock': 'b',
+  });
+
+  itCompilesPackageYarnLockHash('package-yarn-lock', {
+    'package-lock.json': 'a',
+    'yarn.lock': 'b',
+  }, {
+    'package-lock.json': 'a',
+    'yarn.lock': 'c',
+  });
+
+  itCompilesPackageYarnLockHash('package-yarn-lock-2', {
+    'package-lock.json': 'a',
+    'yarn.lock': 'b',
+  }, {
+    'package-lock.json': 'c',
+    'yarn.lock': 'b',
+  });
+
 });