diff --git a/src/compare.ts b/src/compare.ts
index 9bca71f..0b63734 100644
--- a/src/compare.ts
+++ b/src/compare.ts
@@ -1,5 +1,5 @@
-import { compareVersions } from './compareVersions';
-import { CompareOperator } from './utils';
+import { compareVersions } from './compareVersions.js';
+import { CompareOperator } from './utils.js';
 
 /**
  * Compare [semver](https://semver.org/) version strings using the specified operator.
diff --git a/src/compareVersions.ts b/src/compareVersions.ts
index 3321f66..589cbfd 100644
--- a/src/compareVersions.ts
+++ b/src/compareVersions.ts
@@ -1,4 +1,4 @@
-import { compareSegments, validateAndParse } from './utils';
+import { compareSegments, validateAndParse } from './utils.js';
 
 /**
  * Compare [semver](https://semver.org/) version strings to find greater, equal or lesser.
diff --git a/src/index.ts b/src/index.ts
index 6a08240..b2f8aab 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,5 +1,5 @@
-export { compare } from './compare';
-export { compareVersions } from './compareVersions';
-export { satisfies } from './satisfies';
-export { CompareOperator } from './utils';
-export { validate, validateStrict } from './validate';
+export { compare } from './compare.js';
+export { compareVersions } from './compareVersions.js';
+export { satisfies } from './satisfies.js';
+export { CompareOperator } from './utils.js';
+export { validate, validateStrict } from './validate.js';
diff --git a/src/satisfies.ts b/src/satisfies.ts
index 02a9d18..66cb171 100644
--- a/src/satisfies.ts
+++ b/src/satisfies.ts
@@ -1,5 +1,5 @@
-import { compare } from './compare';
-import { CompareOperator, compareSegments, validateAndParse } from './utils';
+import { compare } from './compare.js';
+import { CompareOperator, compareSegments, validateAndParse } from './utils.js';
 
 /**
  * Match [npm semver](https://docs.npmjs.com/cli/v6/using-npm/semver) version range.
diff --git a/src/validate.ts b/src/validate.ts
index db69255..ef91f05 100644
--- a/src/validate.ts
+++ b/src/validate.ts
@@ -1,4 +1,4 @@
-import { semver } from './utils';
+import { semver } from './utils.js';
 
 /**
  * Validate [semver](https://semver.org/) version strings.