diff --git a/packages/replace/src/index.js b/packages/replace/src/index.js
index cd1ff5563..acfb91990 100755
--- a/packages/replace/src/index.js
+++ b/packages/replace/src/index.js
@@ -74,7 +74,7 @@ export default function replace(options = {}) {
   if (objectGuards) expandTypeofReplacements(replacements);
   const functionValues = mapToFunctions(replacements);
   const keys = Object.keys(functionValues).sort(longest).map(escape);
-  const lookahead = preventAssignment ? '(?!\\s*=[^=])' : '';
+  const lookahead = preventAssignment ? '(?!\\s*(=[^=]|:[^:]))' : '';
   const pattern = new RegExp(
     `${delimiters[0]}(${keys.join('|')})${delimiters[1]}${lookahead}`,
     'g'
diff --git a/packages/replace/test/fixtures/form/typescript-declare/_config.js b/packages/replace/test/fixtures/form/typescript-declare/_config.js
new file mode 100755
index 000000000..859fe5f64
--- /dev/null
+++ b/packages/replace/test/fixtures/form/typescript-declare/_config.js
@@ -0,0 +1,8 @@
+module.exports = {
+  description: "doesn't replace lvalue in typescript declare",
+  isTypescript: true,
+  options: {
+    'NAME': 'replaced',
+    preventAssignment: true
+  }
+};
diff --git a/packages/replace/test/fixtures/form/typescript-declare/input.ts b/packages/replace/test/fixtures/form/typescript-declare/input.ts
new file mode 100755
index 000000000..1e39e3e8c
--- /dev/null
+++ b/packages/replace/test/fixtures/form/typescript-declare/input.ts
@@ -0,0 +1,2 @@
+declare const NAME: string
+console.log(NAME)
diff --git a/packages/replace/test/fixtures/form/typescript-declare/output.ts b/packages/replace/test/fixtures/form/typescript-declare/output.ts
new file mode 100755
index 000000000..ea8a01a4f
--- /dev/null
+++ b/packages/replace/test/fixtures/form/typescript-declare/output.ts
@@ -0,0 +1,3 @@
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+declare const NAME: string
+console.log('replaced')
diff --git a/packages/replace/test/form.js b/packages/replace/test/form.js
index 9685dcc99..287a1d508 100644
--- a/packages/replace/test/form.js
+++ b/packages/replace/test/form.js
@@ -21,10 +21,11 @@ readdirSync('./fixtures/form').forEach((dir) => {
 
   test(`${dir}: ${config.description}`, (t) => {
     const { transform } = replace(config.options);
-    const input = readFileSync(`fixtures/form/${dir}/input.js`, 'utf-8');
+    const extname = config.isTypescript ? 'ts' : 'js';
+    const input = readFileSync(`fixtures/form/${dir}/input.${extname}`, 'utf-8');
 
     return Promise.resolve(
-      transform.call(transformContext, input, `${__dirname}/fixtures/form/${dir}/input.js`)
+      transform.call(transformContext, input, `${__dirname}/fixtures/form/${dir}/input.${extname}`)
     ).then((transformed) => {
       const actual = (transformed ? transformed.code : input).trim();
       t.snapshot(actual);
diff --git a/packages/replace/test/snapshots/form.js.md b/packages/replace/test/snapshots/form.js.md
index 0f2bae2c6..cc254b516 100644
--- a/packages/replace/test/snapshots/form.js.md
+++ b/packages/replace/test/snapshots/form.js.md
@@ -86,3 +86,10 @@ Generated by [AVA](https://avajs.dev).
       especial␊
       replaced.doSomething()␊
     \`);`
+
+## typescript-declare: doesn't replace lvalue in typescript declare
+
+> Snapshot 1
+
+    `declare const NAME: string␊
+    console.log(replaced)`
diff --git a/packages/replace/test/snapshots/form.js.snap b/packages/replace/test/snapshots/form.js.snap
index 050826daa..e907e7442 100644
Binary files a/packages/replace/test/snapshots/form.js.snap and b/packages/replace/test/snapshots/form.js.snap differ