diff --git a/lib/Declaration.ts b/lib/Declaration.ts
index 03dff11..3b6954f 100644
--- a/lib/Declaration.ts
+++ b/lib/Declaration.ts
@@ -6,22 +6,15 @@ import ResolutionError from '@error/Resolution';
 import { DeclarationInterface as Interface, File } from '@lib/convert';
 import Path from '@lib/Path';
 
-export interface IOptionsDeclaration<T extends Interface> {
+export interface IDerivedOptions<T extends Interface> {
   declaration: T;
-}
-
-export interface IOptionsFile {
   file: File;
 }
 
-export interface IOptionsPath {
+export interface IOptions<T extends Interface> extends IDerivedOptions<T> {
   path: string;
 }
 
-export type IDerivedOptions<T extends Interface> = IOptionsDeclaration<T> & IOptionsFile;
-
-export type IOptions<T extends Interface> = IDerivedOptions<T> & IOptionsPath;
-
 function isBuiltinModule(module: string): boolean {
   // TODO: change to use 'is-builtin-module', need to submit @types/is-builtin-module
   const builtin = [
diff --git a/lib/File.ts b/lib/File.ts
index 2dd0d9b..d8cb132 100644
--- a/lib/File.ts
+++ b/lib/File.ts
@@ -5,26 +5,16 @@ import FileNotFoundError from '@error/FileNotFound';
 import { Declaration } from '@lib/convert';
 import Path from '@lib/Path';
 
-export interface IOptionsPath {
+export interface IDerivedOptions {
   path: string | Path;
-}
-
-export interface IOptionsOptions {
   options: ICompilerOptions;
-}
-
-export interface IOptionsConfig {
   config: ICompilerConfig;
 }
 
-export interface IOptionsExtension {
+export interface IOptions extends IDerivedOptions {
   extension: string;
 }
 
-export type IDerivedOptions = IOptionsPath & IOptionsOptions & IOptionsConfig;
-
-export type IOptions = IDerivedOptions & IOptionsExtension;
-
 function commonPathPrefix(paths: IterableIterator<string>): string {
   const { done, value: left } = paths.next();
   if (done) {
diff --git a/lib/Mapper.ts b/lib/Mapper.ts
index faf2a47..d7cd313 100644
--- a/lib/Mapper.ts
+++ b/lib/Mapper.ts
@@ -2,13 +2,10 @@ import { existsSync as fileExistsSync, readFileSync as fileReadSync } from 'fs';
 import { dirname, resolve } from 'path';
 import * as ts from 'typescript';
 
-import UnsupportedError from '@error/Unsupported';
-import EsExport from '@es/Export';
+import { Declaration, File } from '@lib/convert';
+
 import EsFile from '@es/File';
-import EsImport from '@es/Import';
-import TsExport from '@ts/Export';
 import TsFile from '@ts/File';
-import TsImport from '@ts/Import';
 
 export interface IOptions {
   tsconfig: string;
@@ -49,14 +46,11 @@ export default class Mapper {
       }));
     }
 
-    if (parsed.options.module !== ts.ModuleKind.ES2015) {
-      throw new UnsupportedError('Only ECMA2015 module outputs are supported at the moment');
-    }
     parsed.options.rootDir = parsed.options.rootDir || projectRoot;
     this.parsed = parsed;
   }
 
-  async *files(): AsyncIterableIterator<EsFile | TsFile> {
+  async *files(): AsyncIterableIterator<File> {
     const { options } = this.parsed;
     yield* this.parsed.fileNames.map(path => new EsFile({ path, options, config: this.parsed }));
     if (options.declaration) {
@@ -64,7 +58,7 @@ export default class Mapper {
     }
   }
 
-  async *map(): AsyncIterableIterator<EsImport | EsExport | TsImport | TsExport> {
+  async *map(): AsyncIterableIterator<Declaration> {
     for await (const file of this.files()) {
       yield* file.map(this.parsed.options);
     }
diff --git a/lib/convert.ts b/lib/convert.ts
index 95aced3..94b4997 100644
--- a/lib/convert.ts
+++ b/lib/convert.ts
@@ -1,13 +1,29 @@
 import EsImport, { Interface as EsImportInterface } from '@es/Export';
 import EsFile from '@es/File';
 import EsExport, { Interface as EsExportInterface } from '@es/Import';
+import EsRequire, { Interface as EsRequireInterface } from '@es/Require';
 import Mapper, { IOptions as IMapperOptions } from '@lib/Mapper';
 import TsImport, { Interface as TsImportInterface } from '@ts/Export';
 import TsFile from '@ts/File';
 import TsExport, { Interface as TsExportInterface } from '@ts/Import';
-export type DeclarationInterface = EsImportInterface | EsExportInterface | TsImportInterface | TsExportInterface;
-export type Declaration = EsImport | EsExport | TsImport | TsExport;
-export type File = EsFile | TsFile;
+
+export type DeclarationInterface =
+ EsRequireInterface |
+  EsImportInterface |
+  EsExportInterface |
+  TsImportInterface |
+  TsExportInterface;
+
+export type Declaration =
+  EsImport |
+  EsExport |
+  TsImport |
+  TsExport |
+  EsRequire;
+
+export type File =
+  EsFile |
+  TsFile;
 
 export type IOptions = IMapperOptions;
 
diff --git a/lib/es/Declaration.ts b/lib/es/Declaration.ts
index 611bef5..30c5b3a 100644
--- a/lib/es/Declaration.ts
+++ b/lib/es/Declaration.ts
@@ -1,27 +1,46 @@
 import { ExportAllDeclaration, ExportNamedDeclaration,  ImportDeclaration, SimpleLiteral } from 'estree';
 
+import isExportNamedDeclaration from '@es/isExportNamedDeclaration';
+import isImportDeclaration from '@es/isImportDeclaration';
+import isRequireCallExpression from '@es/isRequireCallExpression';
+import isSimpleLiteral from '@es/isSimpleLiteral';
+import RequireCallExpression from '@es/RequireCallExpression';
+import { File } from '@lib/convert';
+
 import Base, { IDerivedOptions as IBaseOptions } from '@lib/Declaration';
 
-export type Interface = (ExportAllDeclaration | ExportNamedDeclaration) | ImportDeclaration;
+export type Interface = (ExportAllDeclaration | ExportNamedDeclaration) | ImportDeclaration | RequireCallExpression;
 
 export type IOptions<T extends Interface> = IBaseOptions<T>;
 
+function getLiteral(declaration: Interface, file: File): SimpleLiteral {
+  const literal =
+    isExportNamedDeclaration(declaration) ? declaration.source :
+    isImportDeclaration(declaration) ? declaration.source :
+    isRequireCallExpression(declaration) ? declaration.arguments[0] :
+    undefined;
+  if (literal === undefined) {
+    throw new TypeError(`Failed to find ES declaration in '${file.source}'`);
+  } else if (!isSimpleLiteral(literal)) {
+    const type = literal ? literal.type : 'unknown';
+    throw new TypeError(`Invalid ES declaration source type '${type}' in '${file.source}'`);
+  }
+  return literal;
+}
+
 export default class Declaration<T extends Interface> extends Base<T> {
   constructor({ declaration, file, ...rest}: IOptions<T>) {
     // RAII checks
-    const { type, value } = (declaration.source as SimpleLiteral);
-    if (type !== 'Literal') {
-      throw new TypeError(`Invalid ES declaration source type '${type}' in '${file.source}'`);
-    }
-    if (typeof value !== 'string') {
-      throw new TypeError(`The type '${typeof value}' of the ES source value was not a 'string' for '${file.source}'`);
+    const literal = getLiteral(declaration, file);
+    if (typeof literal.value !== 'string') {
+      throw new TypeError(`The type '${typeof literal.value}' of the ES source must be 'string' for '${file.source}'`);
     }
 
-    super({declaration, file, ...rest, path: value});
+    super({declaration, file, ...rest, path: literal.value});
   }
 
   private get literal(): SimpleLiteral {
-    return (this.declaration.source as SimpleLiteral);
+    return getLiteral(this.declaration, this.file);
   }
 
   get path(): string {
diff --git a/lib/es/File.ts b/lib/es/File.ts
index 47899ce..eb22673 100644
--- a/lib/es/File.ts
+++ b/lib/es/File.ts
@@ -1,11 +1,17 @@
-import { ExportNamedDeclaration, ImportDeclaration, Program } from 'estree';
+import { Program } from 'estree';
 import { PathLike, readFile as readFileSync, writeFile as writeFileSync } from 'fs';
+import { ModuleKind } from 'typescript';
 import { promisify } from 'util';
 
 import ParseError from '@error/Parse';
 import Export from '@es/Export';
 import Import from '@es/Import';
+import isExportNamedDeclaration from '@es/isExportNamedDeclaration';
+import isImportDeclaration from '@es/isImportDeclaration';
+import isRequireCallExpression from '@es/isRequireCallExpression';
+import isVariableDeclaration from '@es/isVariableDeclaration';
 import { attachComments, Comment, generate, parse, plugins, Token } from '@es/parser';
+import Require from '@es/Require';
 import Base, { IDerivedOptions as IBaseOptions } from '@lib/File';
 
 const readFile = promisify(readFileSync);
@@ -13,7 +19,7 @@ const writeFile = promisify(writeFileSync);
 
 export type IOptions = IBaseOptions;
 
-export default class File extends Base<Import, Export> {
+export default class File extends Base<Import | Require, Export> {
   private program: Program | undefined;
 
   constructor({ ...options }: IOptions) {
@@ -35,7 +41,7 @@ export default class File extends Base<Import, Export> {
               ranges: true,
               onComment: comments,
               onToken: tokens,
-              sourceType: 'module',
+              sourceType: this.options.module === ModuleKind.ES2015 ? 'module' : 'script',
               ecmaVersion: 8,
               plugins
             });
@@ -52,25 +58,25 @@ export default class File extends Base<Import, Export> {
     }
   }
 
-  async *imports(): AsyncIterableIterator<Import> {
+  async *imports(): AsyncIterableIterator<Import | Require> {
     const { body } = await this.ast;
     yield* body
-      .filter(({type}) => type === 'ImportDeclaration')
-      .map(n => new Import({file: this, declaration: n as ImportDeclaration}));
+      .filter(isImportDeclaration)
+      .map(declaration => new Import({file: this, declaration}));
+    yield* body
+      .filter(isVariableDeclaration)
+      .map(({declarations}) => declarations)
+      .reduce((a, n) => a.concat(n), [])
+      .map(({init}) => init)
+      .filter(isRequireCallExpression)
+      .map(declaration => new Require({file: this, declaration}));
   }
 
   async *exports(): AsyncIterableIterator<Export> {
     const { body } = await this.ast;
     yield* body
-      .filter(n =>
-        n.type === 'ExportAllDeclaration' ||
-        (n.type === 'ExportNamedDeclaration' && (n).source !== null))
-      .map(n => new Export({
-        file: this,
-        declaration: n.type === 'ExportAllDeclaration' ?
-          n :
-          n as ExportNamedDeclaration
-      }));
+      .filter(isExportNamedDeclaration)
+      .map(declaration => new Export({ file: this, declaration }));
   }
 
   async write(path?: PathLike | number, options?: {
diff --git a/lib/es/Require.ts b/lib/es/Require.ts
new file mode 100644
index 0000000..e60f4a5
--- /dev/null
+++ b/lib/es/Require.ts
@@ -0,0 +1,9 @@
+import RequireCallExpression from '@es/RequireCallExpression';
+
+import Declaration, { IOptions as IDeclarationOptions } from '@es/Declaration';
+
+export type Interface = RequireCallExpression;
+
+export type IOptions = IDeclarationOptions<Interface>;
+
+export default class Require extends Declaration<Interface> {}
diff --git a/lib/es/RequireCallExpression.ts b/lib/es/RequireCallExpression.ts
new file mode 100644
index 0000000..67c5106
--- /dev/null
+++ b/lib/es/RequireCallExpression.ts
@@ -0,0 +1,7 @@
+import { Identifier, SimpleCallExpression, SimpleLiteral } from 'estree';
+
+// tslint:disable-next-line:interface-name
+export default interface RequireCallExpression extends SimpleCallExpression {
+  callee: Identifier;
+  arguments: [ SimpleLiteral ];
+}
diff --git a/lib/es/isExportNamedDeclaration.ts b/lib/es/isExportNamedDeclaration.ts
new file mode 100644
index 0000000..179f2c4
--- /dev/null
+++ b/lib/es/isExportNamedDeclaration.ts
@@ -0,0 +1,8 @@
+import { ExportNamedDeclaration, Node } from 'estree';
+
+export default function isExportNamedDeclaration(data: Node | null | undefined): data is ExportNamedDeclaration {
+  return data !== null &&
+    data !== undefined &&
+    (data.type === 'ExportAllDeclaration'
+      || (data.type === 'ExportNamedDeclaration' && data.source !== null));
+}
diff --git a/lib/es/isIdentifier.ts b/lib/es/isIdentifier.ts
new file mode 100644
index 0000000..41f7205
--- /dev/null
+++ b/lib/es/isIdentifier.ts
@@ -0,0 +1,5 @@
+import { Identifier, Node } from 'estree';
+
+export default function isIdentifier(data: Node | null | undefined): data is Identifier {
+  return data !== null && data !== undefined && data.type === 'Identifier';
+}
diff --git a/lib/es/isImportDeclaration.ts b/lib/es/isImportDeclaration.ts
new file mode 100644
index 0000000..9b5f7bd
--- /dev/null
+++ b/lib/es/isImportDeclaration.ts
@@ -0,0 +1,5 @@
+import { ImportDeclaration, Node } from 'estree';
+
+export default function isImportDeclaration(data: Node | null | undefined): data is ImportDeclaration {
+  return data !== null && data !== undefined && data.type === 'ImportDeclaration';
+}
diff --git a/lib/es/isRequireCallExpression.ts b/lib/es/isRequireCallExpression.ts
new file mode 100644
index 0000000..af12e87
--- /dev/null
+++ b/lib/es/isRequireCallExpression.ts
@@ -0,0 +1,15 @@
+import isIdentifier from '@es/isIdentifier';
+import isSimpleCallExpression from '@es/isSimpleCallExpression';
+import isSimpleLiteral from '@es/isSimpleLiteral';
+import RequireCallExpression from '@es/RequireCallExpression';
+import { Node } from 'estree';
+
+export default function isRequireCallExpression(data: Node | undefined | null): data is RequireCallExpression {
+  return data !== null &&
+    data !== undefined &&
+    isSimpleCallExpression(data) &&
+    isIdentifier(data.callee) &&
+    data.callee.name === 'require' &&
+    data.arguments.length === 1 &&
+    isSimpleLiteral(data.arguments[0]);
+}
diff --git a/lib/es/isSimpleCallExpression.ts b/lib/es/isSimpleCallExpression.ts
new file mode 100644
index 0000000..e5bc279
--- /dev/null
+++ b/lib/es/isSimpleCallExpression.ts
@@ -0,0 +1,5 @@
+import { Node, SimpleCallExpression } from 'estree';
+
+export default function isSimpleCallExpression(data: Node | undefined | null): data is SimpleCallExpression {
+  return data !== null && data !== undefined && data.type === 'CallExpression';
+}
diff --git a/lib/es/isSimpleLiteral.ts b/lib/es/isSimpleLiteral.ts
new file mode 100644
index 0000000..a8456a2
--- /dev/null
+++ b/lib/es/isSimpleLiteral.ts
@@ -0,0 +1,5 @@
+import { Node, SimpleLiteral } from 'estree';
+
+export default function isIdentifier(data: Node | null | undefined): data is SimpleLiteral {
+  return data !== null && data !== undefined && data.type === 'Literal';
+}
diff --git a/lib/es/isVariableDeclaration.ts b/lib/es/isVariableDeclaration.ts
new file mode 100644
index 0000000..27ebc4c
--- /dev/null
+++ b/lib/es/isVariableDeclaration.ts
@@ -0,0 +1,5 @@
+import { Node, VariableDeclaration } from 'estree';
+
+export default function isVariableDeclaration(data: Node | null | undefined): data is VariableDeclaration {
+  return data !== null && data !== undefined && data.type === 'VariableDeclaration';
+}