diff --git a/tslib.es6.js b/tslib.es6.js
index 2c7eaad..ddd87f6 100644
--- a/tslib.es6.js
+++ b/tslib.es6.js
@@ -350,8 +350,8 @@ export function __disposeResources(env) {
 
 export function __rewriteRelativeImportExtension(path, preserveJsx) {
     if (typeof path === "string" && /^\.\.?\//.test(path)) {
-        return path.replace(/\.(tsx)$|(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, tsx, d, ext, cm) {
-            return tsx ? preserveJsx ? ".jsx" : ".js" : d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
+        return path.replace(/\.(tsx)$|((?:\.d)?)((?:\.[^./]+?)?)\.([cm]?)ts$/i, function (m, tsx, d, ext, cm) {
+            return tsx ? preserveJsx ? ".jsx" : ".js" : d && (!ext || !cm) ? m : (d + ext + "." + cm.toLowerCase() + "js");
         });
     }
     return path;
diff --git a/tslib.es6.mjs b/tslib.es6.mjs
index 9c2c3f3..a1d9ef5 100644
--- a/tslib.es6.mjs
+++ b/tslib.es6.mjs
@@ -349,8 +349,8 @@ export function __disposeResources(env) {
 
 export function __rewriteRelativeImportExtension(path, preserveJsx) {
   if (typeof path === "string" && /^\.\.?\//.test(path)) {
-      return path.replace(/\.(tsx)$|(\.d)?(\.[^./]+?)?\.([cm])?ts$/i, function (m, tsx, d, ext, cm) {
-          return tsx ? preserveJsx ? ".jsx" : ".js" : d && (ext && !cm || !ext) ? m : ((d || "") + (ext || "") + "." + (cm || "").toLowerCase() + "js");
+      return path.replace(/\.(tsx)$|((?:\.d)?)((?:\.[^./]+?)?)\.([cm]?)ts$/i, function (m, tsx, d, ext, cm) {
+          return tsx ? preserveJsx ? ".jsx" : ".js" : d && (!ext || !cm) ? m : (d + ext + "." + cm.toLowerCase() + "js");
       });
   }
   return path;