diff --git a/modules/ts-plugins/src/ts-transform-append-extension/index.ts b/modules/ts-plugins/src/ts-transform-append-extension/index.ts
index 21c93a8..886bf05 100644
--- a/modules/ts-plugins/src/ts-transform-append-extension/index.ts
+++ b/modules/ts-plugins/src/ts-transform-append-extension/index.ts
@@ -39,18 +39,14 @@ export default function (
     extMappings.set(base, addition);
   }
 
-  function shouldMutateModuleSpecifier(node: Node): string | false {
-    if (!ts.isImportDeclaration(node) && !ts.isExportDeclaration(node)) return false;
-    if (node.moduleSpecifier === undefined) return false;
-    // only when module specifier is valid
-    if (!ts.isStringLiteral(node.moduleSpecifier)) return false;
+  function shouldMutateImportSource(node: Node | undefined): string | false {
+    if (!node || !ts.isStringLiteral(node)) return false;
     // only when path is relative
-    if (!node.moduleSpecifier.text.startsWith('./') && !node.moduleSpecifier.text.startsWith('../'))
-      return false;
+    if (!node.text.startsWith('./') && !node.text.startsWith('../')) return false;
     // only when module specifier has accepted extension
-    const ext = path.extname(node.moduleSpecifier.text);
+    const ext = path.extname(node.text);
     if (!extMappings.has(ext)) return false;
-    return node.moduleSpecifier.text + extMappings.get(ext);
+    return node.text + extMappings.get(ext);
   }
 
   return (ctx: TransformationContext) => {
@@ -58,9 +54,9 @@ export default function (
 
     return (sourceFile: SourceFile) => {
       function visit(node: Node): Node {
-        const newImportSource = shouldMutateModuleSpecifier(node);
-        if (newImportSource) {
-          if (ts.isImportDeclaration(node)) {
+        if (ts.isImportDeclaration(node)) {
+          const newImportSource = shouldMutateImportSource(node.moduleSpecifier);
+          if (newImportSource) {
             const newModuleSpecifier = factory.createStringLiteral(newImportSource);
             node = factory.updateImportDeclaration(
               node,
@@ -69,7 +65,10 @@ export default function (
               newModuleSpecifier,
               node.assertClause
             );
-          } else if (ts.isExportDeclaration(node)) {
+          }
+        } else if (ts.isExportDeclaration(node)) {
+          const newImportSource = shouldMutateImportSource(node.moduleSpecifier);
+          if (newImportSource) {
             const newModuleSpecifier = factory.createStringLiteral(newImportSource);
             node = factory.updateExportDeclaration(
               node,
@@ -80,6 +79,16 @@ export default function (
               node.assertClause
             );
           }
+        } else if (
+          ts.isCallExpression(node) &&
+          node.expression.kind === ts.SyntaxKind.ImportKeyword
+        ) {
+          const newImportSource = shouldMutateImportSource(node.arguments[0]);
+          if (newImportSource) {
+            const newArgs = node.arguments.slice();
+            newArgs[0] = factory.createStringLiteral(newImportSource);
+            node = factory.updateCallExpression(node, node.expression, node.typeArguments, newArgs);
+          }
         }
 
         return ts.visitEachChild(node, visit, ctx);
diff --git a/modules/ts-plugins/test/test-transformer.ts b/modules/ts-plugins/test/test-transformer.ts
index 747626f..7744954 100644
--- a/modules/ts-plugins/test/test-transformer.ts
+++ b/modules/ts-plugins/test/test-transformer.ts
@@ -68,7 +68,7 @@ export function assertSourceEqual(
      */
     ignoreEmptyLines?: boolean;
   } = {}
-): true | Error {
+): true | string {
   const {ignoreIndent = true, ignoreEmptyLines = true} = options;
   const actualLines = actual.split('\n');
   const expectedLines = expected.split('\n');
@@ -90,10 +90,9 @@ export function assertSourceEqual(
     } else if (ignoreEmptyLines && !t2) {
       i2++;
     } else {
-      return new Error(`Mismatch at line ${i1}
+      return `Mismatch at line ${i1}
     Actual: ${t1}
-  Expected: ${t2}
-      `);
+    Expected: ${t2}`;
     }
   }
   return true;
diff --git a/modules/ts-plugins/test/ts-transform-append-extension.spec.ts b/modules/ts-plugins/test/ts-transform-append-extension.spec.ts
index 78bd34a..068bd6f 100644
--- a/modules/ts-plugins/test/ts-transform-append-extension.spec.ts
+++ b/modules/ts-plugins/test/ts-transform-append-extension.spec.ts
@@ -3,17 +3,23 @@ import {transpile, assertSourceEqual} from './test-transformer.js';
 // @ts-expect-error Aliased import, remapped to valid path in esm-loader
 import appendExtension from '@vis.gl/ts-plugins/ts-transform-append-extension';
 
-const input = `\
+const input1 = `\
 export type { TypedArray } from "./types";
 export { add } from "./math/add";
 import vs from "../shaders/vs.glsl";
 import { Shader } from "@luma.gl/core";
 export { vs, Shader };`;
 
+const input2 = `\
+const throttle = await import("lodash.throttle");
+const Matrix4 = import("./math/matrix4");
+import("./shaders").then((modules) => { });`;
+
 const testCases = [
   {
     title: 'add default extension to js imports',
     config: {after: true},
+    input: input1,
     output: `\
 export { add } from "./math/add.js";
 import vs from "../shaders/vs.glsl";
@@ -23,6 +29,7 @@ export { vs, Shader };`
   {
     title: 'add default extension to d.ts imports',
     config: {afterDeclarations: true},
+    input: input1,
     output: `\
 export type { TypedArray } from "./types.js";
 export { add } from "./math/add.js";
@@ -33,18 +40,28 @@ export { vs, Shader };`
   {
     title: 'add custom extension to js imports',
     config: {after: true, extensions: ['.mjs', '.glsl.mjs']},
+    input: input1,
     output: `\
 export { add } from "./math/add.mjs";
 import vs from "../shaders/vs.glsl.mjs";
 import { Shader } from "@luma.gl/core";
 export { vs, Shader };`
+  },
+  {
+    title: 'dynamic imports',
+    config: {after: true},
+    input: input2,
+    output: `\
+const throttle = await import("lodash.throttle");
+const Matrix4 = import("./math/matrix4.js");
+import("./shaders.js").then((modules) => { });`
   }
 ];
 
 test('ts-transform-append-extension', (t) => {
   for (const testCase of testCases) {
     const result = transpile({
-      source: input,
+      source: testCase.input,
       transformer: appendExtension,
       config: testCase.config,
       outputType: testCase.config.afterDeclarations ? 'd.ts' : 'js'