diff --git a/README.md b/README.md
index 7969ab7..4ed1e78 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,9 @@ const tree = dependencyTree({
   }, // optional
   filter: path => path.indexOf('node_modules') === -1, // optional
   nonExistent: [], // optional
-  noTypeDefinitions: false // optional
+  noTypeDefinitions: false, // optional
+  includeCore: false, // optional, if true include node.js core modules (for example: "fs"), they will be prefixed with ':!EXISTS: '
+  includeNonExisting: false // optional, if true include unresolved dependencies, they will be prefixed with ':!EXISTS: '
 });
 
 // Returns a post-order traversal (list form) of the tree with duplicate sub-trees pruned.
diff --git a/index.js b/index.js
index 7b3ca6e..c126fd5 100644
--- a/index.js
+++ b/index.js
@@ -83,7 +83,7 @@ module.exports.toList = function(options = {}) {
  */
 module.exports._getDependencies = function(config = {}) {
   const precinctOptions = config.detectiveConfig;
-  precinctOptions.includeCore = false;
+
   let dependencies;
 
   try {
@@ -113,7 +113,12 @@ module.exports._getDependencies = function(config = {}) {
 
     if (!result) {
       debug(`skipping an empty filepath resolution for partial: ${dependency}`);
+
       config.nonExistent.push(dependency);
+      if (config.includeNonExisting) {
+        resolvedDependencies.push(`:!EXISTS: ${dependency}`);
+      }
+
       continue;
     }
 
@@ -122,6 +127,11 @@ module.exports._getDependencies = function(config = {}) {
     if (!exists) {
       config.nonExistent.push(dependency);
       debug(`skipping non-empty but non-existent resolution: ${result} for partial: ${dependency}`);
+
+      if (config.includeNonExisting) {
+        resolvedDependencies.push(`:!EXISTS: ${dependency}`);
+      }
+
       continue;
     }
 
diff --git a/lib/config.js b/lib/config.js
index b0ba90a..c4a89b2 100644
--- a/lib/config.js
+++ b/lib/config.js
@@ -16,11 +16,15 @@ module.exports = class Config {
     this.requireConfig = options.config || options.requireConfig;
     this.webpackConfig = options.webpackConfig;
     this.nodeModulesConfig = options.nodeModulesConfig;
-    this.detectiveConfig = options.detective || options.detectiveConfig || {};
+    this.includeCore = options.includeCore || false;
+    this.includeNonExisting = options.includeNonExisting || options.includeCore || false;
     this.tsConfig = options.tsConfig;
     this.tsConfigPath = options.tsConfigPath;
     this.noTypeDefinitions = options.noTypeDefinitions;
     this.filter = options.filter;
+    this.detectiveConfig = options.detective || options.detectiveConfig || {};
+    this.detectiveConfig.includeCore = this.includeCore;
+    this.detectiveConfig.includeNonExisting = this.includeNonExisting;
 
     if (!this.filename) throw new Error('filename not given');
     if (!this.directory) throw new Error('directory not given');
diff --git a/test/test.mjs b/test/test.mjs
index 8a97d8d..36ccef9 100644
--- a/test/test.mjs
+++ b/test/test.mjs
@@ -221,6 +221,26 @@ describe('dependencyTree', () => {
     assert.ok(!list.includes(path.join(directory, 'required.js')));
   });
 
+  it('test includeNonExisting=true', () => {
+    const directory = path.join(__dirname, '/fixtures/onlyRealDeps');
+    const filename = path.normalize(`${directory}/a.js`);
+
+    const tree = dependencyTree({ filename, directory, includeNonExisting: true });
+    const subTree = tree[filename];
+
+    assert.ok(Object.keys(subTree).includes(':!EXISTS: not-real'));
+  });
+
+  it('test includeCore=true', () => {
+    const directory = path.join(__dirname, '/fixtures/onlyRealDeps');
+    const filename = path.normalize(`${directory}/a.js`);
+
+    const tree = dependencyTree({ filename, directory, includeCore: true });
+    const subTree = tree[filename];
+
+    assert.ok(Object.keys(subTree).includes(':!EXISTS: path'));
+  });
+
   describe('when given a detective configuration', () => {
     it('passes it through to precinct', () => {
       const spy = sinon.spy(precinct, 'paperwork');