diff --git a/README.md b/README.md
index 7a58f52..146d8a5 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@ Consumers should use the exported `extensions` or `jsVariants` object to determi
 
 1.  If the value is null, do nothing.
 2.  If the value is a string, try to require it.
-3.  If the value is an object, try to require the `module` property. If successful, the `register` property (a function) should be called with the module passed as the first argument.
+3.  If the value is an object, try to require the `module` property. If successful, the `register` property (a function) should be called with the module passed as the first argument. **Advanced:** An optional second argument can be provided to replace the default configuration for a hook.
 4.  If the value is an array, iterate over it, attempting step #2 or #3 until one of the attempts does not throw.
 
 ## API
diff --git a/index.js b/index.js
index 4cb8083..8c79279 100644
--- a/index.js
+++ b/index.js
@@ -70,44 +70,73 @@ function isNodeModules(file) {
 var extensions = {
   '.babel.js': {
     module: '@babel/register',
-    register: function (hook) {
-      hook({
-        extensions: '.js',
+    register: function (hook, config) {
+      config = config || {
         rootMode: 'upward-optional',
-        overrides: [{ only: [endsInBabelJs] }],
-      });
+        overrides: [{ only: [endsInBabelJs], presets: ['@babel/preset-env'] }],
+      };
+
+      hook(Object.assign({}, config, { extensions: '.js' }));
     },
   },
   '.babel.jsx': {
     module: '@babel/register',
-    register: function (hook) {
-      hook({
-        extensions: '.jsx',
+    register: function (hook, config) {
+      config = config || {
         rootMode: 'upward-optional',
-        overrides: [{ only: [endsInBabelJsx] }],
-      });
+        overrides: [
+          {
+            only: [endsInBabelJsx],
+            presets: ['@babel/preset-env', '@babel/preset-react'],
+          },
+        ],
+      };
+
+      hook(Object.assign({}, config, { extensions: '.jsx' }));
     },
   },
   '.babel.ts': [
     {
       module: '@babel/register',
-      register: function (hook) {
-        hook({
-          extensions: '.ts',
+      register: function (hook, config) {
+        config = config || {
           rootMode: 'upward-optional',
-          overrides: [{ only: [endsInBabelTs] }],
-        });
+          overrides: [
+            {
+              only: [endsInBabelTs],
+              presets: ['@babel/preset-env', '@babel/preset-typescript'],
+            },
+          ],
+        };
+
+        hook(Object.assign({}, config, { extensions: '.ts' }));
       },
     },
   ],
   '.babel.tsx': {
     module: '@babel/register',
-    register: function (hook) {
-      hook({
-        extensions: '.tsx',
+    register: function (hook, config) {
+      config = config || {
         rootMode: 'upward-optional',
-        overrides: [{ only: [endsInBabelTsx] }],
-      });
+        overrides: [
+          {
+            only: [endsInBabelTsx],
+            presets: [
+              '@babel/preset-env',
+              '@babel/preset-react',
+              [
+                '@babel/preset-typescript',
+                {
+                  isTSX: true,
+                  allExtensions: true,
+                },
+              ],
+            ],
+          },
+        ],
+      };
+
+      hook(Object.assign({}, config, { extensions: '.tsx' }));
     },
   },
   '.cjs': cjsStub,
@@ -115,42 +144,46 @@ var extensions = {
   '.coffee.md': 'coffeescript/register',
   '.esbuild.js': {
     module: 'esbuild-register/dist/node',
-    register: function (mod) {
-      mod.register({
-        extensions: ['.js'],
+    register: function (mod, config) {
+      config = config || {
         target: 'node' + process.version.slice(1),
         hookMatcher: endsInEsbuildJs,
-      });
+      };
+
+      mod.register(Object.assign({}, config, { extensions: ['.js'] }));
     },
   },
   '.esbuild.jsx': {
     module: 'esbuild-register/dist/node',
-    register: function (mod) {
-      mod.register({
-        extensions: ['.jsx'],
+    register: function (mod, config) {
+      config = config || {
         target: 'node' + process.version.slice(1),
         hookMatcher: endsInEsbuildJsx,
-      });
+      };
+
+      mod.register(Object.assign({}, config, { extensions: ['.jsx'] }));
     },
   },
   '.esbuild.ts': {
     module: 'esbuild-register/dist/node',
-    register: function (mod) {
-      mod.register({
-        extensions: ['.ts'],
+    register: function (mod, config) {
+      config = config || {
         target: 'node' + process.version.slice(1),
         hookMatcher: endsInEsbuildTs,
-      });
+      };
+
+      mod.register(Object.assign({}, config, { extensions: ['.ts'] }));
     },
   },
   '.esbuild.tsx': {
     module: 'esbuild-register/dist/node',
-    register: function (mod) {
-      mod.register({
-        extensions: ['.tsx'],
+    register: function (mod, config) {
+      config = config || {
         target: 'node' + process.version.slice(1),
         hookMatcher: endsInEsbuildTsx,
-      });
+      };
+
+      mod.register(Object.assign({}, config, { extensions: ['.tsx'] }));
     },
   },
   '.esm.js': {
@@ -168,12 +201,18 @@ var extensions = {
   '.jsx': [
     {
       module: '@babel/register',
-      register: function (hook) {
-        hook({
-          extensions: '.jsx',
+      register: function (hook, config) {
+        config = config || {
           rootMode: 'upward-optional',
-          overrides: [{ only: [endsInJsx] }],
-        });
+          overrides: [
+            {
+              only: [endsInJsx],
+              presets: ['@babel/preset-env', '@babel/preset-react'],
+            },
+          ],
+        };
+
+        hook(Object.assign({}, config, { extensions: '.jsx' }));
       },
     },
     'sucrase/register/jsx',
@@ -186,80 +225,142 @@ var extensions = {
   '.node': null,
   '.sucrase.js': {
     module: 'sucrase/dist/register',
-    register: function (hook) {
-      hook.registerJS({
+    register: function (hook, config) {
+      config = config || {
         matcher: endsInSucraseJs,
-      });
+      };
+
+      hook.registerJS(config);
     },
   },
   '.sucrase.jsx': {
     module: 'sucrase/dist/register',
-    register: function (hook) {
-      hook.registerJSX({
+    register: function (hook, config) {
+      config = config || {
         matcher: endsInSucraseJsx,
-      });
+      };
+
+      hook.registerJSX(config);
     },
   },
   '.sucrase.ts': {
     module: 'sucrase/dist/register',
-    register: function (hook) {
-      hook.registerTS({
+    register: function (hook, config) {
+      config = config || {
         matcher: endsInSucraseTs,
-      });
+      };
+
+      hook.registerTS(config);
     },
   },
   '.sucrase.tsx': {
     module: 'sucrase/dist/register',
-    register: function (hook) {
-      hook.registerTSX({
+    register: function (hook, config) {
+      config = config || {
         matcher: endsInSucraseTsx,
-      });
+      };
+
+      hook.registerTSX(config);
     },
   },
   '.swc.js': {
     module: '@swc/register',
-    register: function (hook) {
-      hook({
-        extensions: '.js',
+    register: function (hook, config) {
+      config = config || {
         only: [endsInSwcJs],
         ignore: [isNodeModules],
-      });
+        jsc: {
+          parser: {
+            syntax: 'ecmascript',
+          },
+        },
+        module: {
+          type: 'commonjs',
+        },
+      };
+
+      hook(
+        Object.assign({}, config, {
+          extensions: '.js',
+        })
+      );
     },
   },
   '.swc.jsx': {
     module: '@swc/register',
-    register: function (hook) {
-      hook({
-        extensions: '.jsx',
+    register: function (hook, config) {
+      config = config || {
         only: [endsInSwcJsx],
         ignore: [isNodeModules],
-      });
+        jsc: {
+          parser: {
+            syntax: 'ecmascript',
+            jsx: true,
+          },
+        },
+        module: {
+          type: 'commonjs',
+        },
+      };
+
+      hook(
+        Object.assign({}, config, {
+          extensions: '.jsx',
+        })
+      );
     },
   },
   '.swc.ts': {
     module: '@swc/register',
-    register: function (hook) {
-      hook({
-        extensions: '.ts',
+    register: function (hook, config) {
+      config = config || {
         only: [endsInSwcTs],
         ignore: [isNodeModules],
-      });
+        jsc: {
+          parser: {
+            syntax: 'typescript',
+          },
+        },
+        module: {
+          type: 'commonjs',
+        },
+      };
+
+      hook(
+        Object.assign({}, config, {
+          extensions: '.ts',
+        })
+      );
     },
   },
   '.swc.tsx': {
     module: '@swc/register',
-    register: function (hook) {
-      hook({
-        extensions: '.tsx',
+    register: function (hook, config) {
+      config = config || {
         only: [endsInSwcTsx],
         ignore: [isNodeModules],
-      });
+        jsc: {
+          parser: {
+            syntax: 'typescript',
+            tsx: true,
+          },
+        },
+        module: {
+          type: 'commonjs',
+        },
+      };
+
+      hook(
+        Object.assign({}, config, {
+          extensions: '.tsx',
+        })
+      );
     },
   },
   '.toml': {
     module: 'toml-require',
-    register: function (hook) {
-      hook.install();
+    register: function (hook, config) {
+      hook.install(config);
     },
   },
   '.ts': [
@@ -267,32 +368,60 @@ var extensions = {
     'sucrase/register/ts',
     {
       module: '@babel/register',
-      register: function (hook) {
-        hook({
-          extensions: '.ts',
+      register: function (hook, config) {
+        config = config || {
           rootMode: 'upward-optional',
-          overrides: [{ only: [endsInTs] }],
-        });
+          overrides: [
+            {
+              only: [endsInTs],
+              presets: ['@babel/preset-env', '@babel/preset-typescript'],
+            },
+          ],
+        };
+
+        hook(
+          Object.assign({}, config, {
+            extensions: '.ts',
+          })
+        );
       },
     },
     {
       module: 'esbuild-register/dist/node',
-      register: function (mod) {
-        mod.register({
-          extensions: ['.ts'],
+      register: function (mod, config) {
+        config = config || {
           target: 'node' + process.version.slice(1),
           hookMatcher: endsInTs,
-        });
+        };
+
+        mod.register(
+          Object.assign({}, config, {
+            extensions: ['.ts'],
+          })
+        );
       },
     },
     {
       module: '@swc/register',
-      register: function (hook) {
-        hook({
-          extensions: '.ts',
+      register: function (hook, config) {
+        config = config || {
           only: [endsInTs],
           ignore: [isNodeModules],
-        });
+          jsc: {
+            parser: {
+              syntax: 'typescript',
+            },
+          },
+          module: {
+            type: 'commonjs',
+          },
+        };
+
+        hook(
+          Object.assign({}, config, {
+            extensions: '.ts',
+          })
+        );
       },
     },
   ],
@@ -301,32 +430,71 @@ var extensions = {
     'sucrase/register/tsx',
     {
       module: '@babel/register',
-      register: function (hook) {
-        hook({
-          extensions: '.tsx',
+      register: function (hook, config) {
+        config = config || {
           rootMode: 'upward-optional',
-          overrides: [{ only: [endsInTsx] }],
-        });
+          overrides: [
+            {
+              only: [endsInTsx],
+              presets: [
+                '@babel/preset-env',
+                '@babel/preset-react',
+                [
+                  '@babel/preset-typescript',
+                  {
+                    isTSX: true,
+                    allExtensions: true,
+                  },
+                ],
+              ],
+            },
+          ],
+        };
+
+        hook(
+          Object.assign({}, config, {
+            extensions: '.tsx',
+          })
+        );
       },
     },
     {
       module: 'esbuild-register/dist/node',
-      register: function (mod) {
-        mod.register({
-          extensions: ['.tsx'],
+      register: function (mod, config) {
+        config = config || {
           target: 'node' + process.version.slice(1),
           hookMatcher: endsInTsx,
-        });
+        };
+
+        mod.register(
+          Object.assign({}, config, {
+            extensions: ['.tsx'],
+          })
+        );
       },
     },
     {
       module: '@swc/register',
-      register: function (hook) {
-        hook({
-          extensions: '.tsx',
+      register: function (hook, config) {
+        config = config || {
           only: [endsInTsx],
           ignore: [isNodeModules],
-        });
+          jsc: {
+            parser: {
+              syntax: 'typescript',
+              tsx: true,
+            },
+          },
+          module: {
+            type: 'commonjs',
+          },
+        };
+
+        hook(
+          Object.assign({}, config, {
+            extensions: '.tsx',
+          })
+        );
       },
     },
   ],
diff --git a/test/fixtures/babel.js/0/.babelrc b/test/fixtures/babel.js/0/.babelrc
deleted file mode 100644
index 7dd5e9d..0000000
--- a/test/fixtures/babel.js/0/.babelrc
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "presets": ["@babel/preset-react"]
-}
diff --git a/test/fixtures/babel.js/0/package.json b/test/fixtures/babel.js/0/package.json
index 3d1a2a6..c98805b 100644
--- a/test/fixtures/babel.js/0/package.json
+++ b/test/fixtures/babel.js/0/package.json
@@ -1,7 +1,7 @@
 {
   "dependencies": {
     "@babel/core": "^7.2.2",
-    "@babel/preset-react": "^7.0.0",
+    "@babel/preset-env": "^7.0.0",
     "@babel/register": "^7.0.0"
   }
 }
diff --git a/test/fixtures/babel.jsx/0/.babelrc b/test/fixtures/babel.jsx/0/.babelrc
deleted file mode 100644
index 7dd5e9d..0000000
--- a/test/fixtures/babel.jsx/0/.babelrc
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "presets": ["@babel/preset-react"]
-}
diff --git a/test/fixtures/babel.jsx/0/package.json b/test/fixtures/babel.jsx/0/package.json
index 3d1a2a6..cec293f 100644
--- a/test/fixtures/babel.jsx/0/package.json
+++ b/test/fixtures/babel.jsx/0/package.json
@@ -1,6 +1,7 @@
 {
   "dependencies": {
     "@babel/core": "^7.2.2",
+    "@babel/preset-env": "^7.0.0",
     "@babel/preset-react": "^7.0.0",
     "@babel/register": "^7.0.0"
   }
diff --git a/test/fixtures/babel.ts/0/.babelrc b/test/fixtures/babel.ts/0/.babelrc
deleted file mode 100644
index e15ac01..0000000
--- a/test/fixtures/babel.ts/0/.babelrc
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "presets": ["@babel/preset-typescript"]
-}
diff --git a/test/fixtures/babel.ts/0/package.json b/test/fixtures/babel.ts/0/package.json
index 6298ebf..71c22d5 100644
--- a/test/fixtures/babel.ts/0/package.json
+++ b/test/fixtures/babel.ts/0/package.json
@@ -1,6 +1,7 @@
 {
   "dependencies": {
     "@babel/core": "^7.2.2",
+    "@babel/preset-env": "^7.0.0",
     "@babel/preset-typescript": "^7.1.0",
     "@babel/register": "^7.0.0"
   }
diff --git a/test/fixtures/babel.tsx/0/.babelrc b/test/fixtures/babel.tsx/0/.babelrc
deleted file mode 100644
index 5bcced6..0000000
--- a/test/fixtures/babel.tsx/0/.babelrc
+++ /dev/null
@@ -1,13 +0,0 @@
-{
-  "presets": [
-    "@babel/preset-env",
-    "@babel/preset-react",
-    [
-      "@babel/preset-typescript",
-      {
-        "isTSX": true,
-        "allExtensions": true
-      }
-    ]
-  ]
-}
diff --git a/test/fixtures/jsx/0/.babelrc b/test/fixtures/jsx/0/.babelrc
deleted file mode 100644
index 7dd5e9d..0000000
--- a/test/fixtures/jsx/0/.babelrc
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "presets": ["@babel/preset-react"]
-}
diff --git a/test/fixtures/jsx/0/package.json b/test/fixtures/jsx/0/package.json
index 3d1a2a6..cec293f 100644
--- a/test/fixtures/jsx/0/package.json
+++ b/test/fixtures/jsx/0/package.json
@@ -1,6 +1,7 @@
 {
   "dependencies": {
     "@babel/core": "^7.2.2",
+    "@babel/preset-env": "^7.0.0",
     "@babel/preset-react": "^7.0.0",
     "@babel/register": "^7.0.0"
   }
diff --git a/test/fixtures/swc.js/0/.swcrc b/test/fixtures/swc.js/0/.swcrc
deleted file mode 100644
index a38ca9b..0000000
--- a/test/fixtures/swc.js/0/.swcrc
+++ /dev/null
@@ -1,10 +0,0 @@
-{
-  "jsc": {
-    "parser": {
-      "syntax": "ecmascript"
-    }
-  },
-  "module": {
-    "type": "commonjs"
-  }
-}
diff --git a/test/fixtures/swc.jsx/0/.swcrc b/test/fixtures/swc.jsx/0/.swcrc
deleted file mode 100644
index 89600e0..0000000
--- a/test/fixtures/swc.jsx/0/.swcrc
+++ /dev/null
@@ -1,11 +0,0 @@
-{
-  "jsc": {
-    "parser": {
-      "syntax": "ecmascript",
-      "jsx": true
-    }
-  },
-  "module": {
-    "type": "commonjs"
-  }
-}
diff --git a/test/fixtures/swc.ts/0/.swcrc b/test/fixtures/swc.ts/0/.swcrc
deleted file mode 100644
index a9c9497..0000000
--- a/test/fixtures/swc.ts/0/.swcrc
+++ /dev/null
@@ -1,10 +0,0 @@
-{
-  "jsc": {
-    "parser": {
-      "syntax": "typescript"
-    }
-  },
-  "module": {
-    "type": "commonjs"
-  }
-}
diff --git a/test/fixtures/swc.tsx/0/.swcrc b/test/fixtures/swc.tsx/0/.swcrc
deleted file mode 100644
index 98f536d..0000000
--- a/test/fixtures/swc.tsx/0/.swcrc
+++ /dev/null
@@ -1,11 +0,0 @@
-{
-  "jsc": {
-    "parser": {
-      "syntax": "typescript",
-      "tsx": true
-    }
-  },
-  "module": {
-    "type": "commonjs"
-  }
-}
diff --git a/test/fixtures/ts/2/.babelrc b/test/fixtures/ts/2/.babelrc
deleted file mode 100644
index 5bcced6..0000000
--- a/test/fixtures/ts/2/.babelrc
+++ /dev/null
@@ -1,13 +0,0 @@
-{
-  "presets": [
-    "@babel/preset-env",
-    "@babel/preset-react",
-    [
-      "@babel/preset-typescript",
-      {
-        "isTSX": true,
-        "allExtensions": true
-      }
-    ]
-  ]
-}
diff --git a/test/fixtures/ts/2/component.ts b/test/fixtures/ts/2/component.ts
deleted file mode 100644
index d26bcf1..0000000
--- a/test/fixtures/ts/2/component.ts
+++ /dev/null
@@ -1,18 +0,0 @@
-const React = {
-  createElement(Component: () => any) {
-    return Component();
-  },
-};
-
-// Test harmony arrow functions.
-const Component = () => {
-  var trueKey: boolean = true;
-  var falseKey: boolean = false;
-  var subKey = { subProp: 1 };
-
-  // Test harmony object short notation.
-  return { data: { trueKey, falseKey, subKey } };
-};
-
-// Test TSX syntax.
-export default <Component />;
diff --git a/test/fixtures/ts/2/package.json b/test/fixtures/ts/2/package.json
index 5fa8c33..cc3213f 100644
--- a/test/fixtures/ts/2/package.json
+++ b/test/fixtures/ts/2/package.json
@@ -2,7 +2,6 @@
   "dependencies": {
     "@babel/core": "^7.2.2",
     "@babel/preset-env": "^7.2.3",
-    "@babel/preset-react": "^7.0.0",
     "@babel/preset-typescript": "^7.1.0",
     "@babel/register": "^7.0.0"
   }
diff --git a/test/fixtures/ts/2/test.ts b/test/fixtures/ts/2/test.ts
index 28103e5..3fa0969 100644
--- a/test/fixtures/ts/2/test.ts
+++ b/test/fixtures/ts/2/test.ts
@@ -1,5 +1,19 @@
-import Component from './component';
-
-var test: typeof Component = { ...Component };
+var test: {
+  data: {
+    trueKey: boolean;
+    falseKey: boolean;
+    subKey: {
+      subProp: number;
+    };
+  };
+} = {
+  data: {
+    trueKey: true,
+    falseKey: false,
+    subKey: {
+      subProp: 1,
+    },
+  },
+};
 
 export default test;
diff --git a/test/fixtures/ts/4/.swcrc b/test/fixtures/ts/4/.swcrc
deleted file mode 100644
index a9c9497..0000000
--- a/test/fixtures/ts/4/.swcrc
+++ /dev/null
@@ -1,10 +0,0 @@
-{
-  "jsc": {
-    "parser": {
-      "syntax": "typescript"
-    }
-  },
-  "module": {
-    "type": "commonjs"
-  }
-}
diff --git a/test/fixtures/tsx/2/.babelrc b/test/fixtures/tsx/2/.babelrc
deleted file mode 100644
index 5bcced6..0000000
--- a/test/fixtures/tsx/2/.babelrc
+++ /dev/null
@@ -1,13 +0,0 @@
-{
-  "presets": [
-    "@babel/preset-env",
-    "@babel/preset-react",
-    [
-      "@babel/preset-typescript",
-      {
-        "isTSX": true,
-        "allExtensions": true
-      }
-    ]
-  ]
-}
diff --git a/test/fixtures/tsx/4/.swcrc b/test/fixtures/tsx/4/.swcrc
deleted file mode 100644
index 98f536d..0000000
--- a/test/fixtures/tsx/4/.swcrc
+++ /dev/null
@@ -1,11 +0,0 @@
-{
-  "jsc": {
-    "parser": {
-      "syntax": "typescript",
-      "tsx": true
-    }
-  },
-  "module": {
-    "type": "commonjs"
-  }
-}