diff --git a/tslib.es6.js b/tslib.es6.js
index 36b58a5..5b36110 100644
--- a/tslib.es6.js
+++ b/tslib.es6.js
@@ -357,10 +357,9 @@ export function __rewriteRelativeImportExtension(path, preserveJsx) {
         if (extMatch) {
             var ext = extMatch[0].toLowerCase();
             var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
-            if (dot >= 0 && (path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
-                return path;
+            if (dot < 0 || !(path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
+                return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
             }
-            return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
         }
     }
     return path;
diff --git a/tslib.es6.mjs b/tslib.es6.mjs
index ccffef3..7fed569 100644
--- a/tslib.es6.mjs
+++ b/tslib.es6.mjs
@@ -356,10 +356,9 @@ export function __rewriteRelativeImportExtension(path, preserveJsx) {
       if (extMatch) {
           var ext = extMatch[0].toLowerCase();
           var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
-          if (dot >= 0 && (path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
-              return path;
+          if (dot < 0 || !(path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
+              return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
           }
-          return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
       }
   }
   return path;
diff --git a/tslib.js b/tslib.js
index 64090f0..d22e885 100644
--- a/tslib.js
+++ b/tslib.js
@@ -405,10 +405,9 @@ var __rewriteRelativeImportExtension;
             if (extMatch) {
                 var ext = extMatch[0].toLowerCase();
                 var dot = path.lastIndexOf(".", path.length - (ext.length + 1));
-                if (dot >= 0 && (path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
-                    return path;
+                if (dot < 0 || !(path.substring(dot - 2, dot).toLowerCase() === ".d" || path.substring(dot, dot + 2).toLowerCase() === ".d")) {
+                    return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
                 }
-                return path.substring(0, path.length - ext.length) + (ext === ".mts" ? ".mjs" : ext === ".cts" ? ".cjs" : ".js");
             }
         }
         return path;