diff --git a/src/puter-js/test/apps.test.js b/src/puter-js/test/apps.test.js
index 5846e4d75..6ab20ef2d 100644
--- a/src/puter-js/test/apps.test.js
+++ b/src/puter-js/test/apps.test.js
@@ -37,7 +37,9 @@ window.appsTests = [
                 });
                 const fetched = await puter.apps.get(name);
                 assert(Boolean(fetched.maximize_on_start) === true, "maximize_on_start not stored");
-                assert(JSON.stringify(fetched.filetype_associations) === JSON.stringify(['.txt', 'image/png']), "filetype_associations not stored");
+                // Extensions are canonicalized to the bare lowercase form on
+                // write ('.txt' → 'txt'); MIME types pass through unchanged.
+                assert(JSON.stringify(fetched.filetype_associations) === JSON.stringify(['txt', 'image/png']), "filetype_associations not stored");
                 pass("testCreateOptionsRemap passed");
             } catch (error) {
                 fail("testCreateOptionsRemap failed:", error);
diff --git a/src/puter-js/tests/api/suites/apps.suite.ts b/src/puter-js/tests/api/suites/apps.suite.ts
index 8d9c55ed2..ea01e30fd 100644
--- a/src/puter-js/tests/api/suites/apps.suite.ts
+++ b/src/puter-js/tests/api/suites/apps.suite.ts
@@ -222,7 +222,9 @@ export default suite('apps', {
             maximizeOnStart: true,
         });
         const fetched = await t.puter.apps.get('apps-suite-remap');
-        t.assert.deepEqual(fetched.filetype_associations, ['.txt', 'image/png']);
+        // Extensions are canonicalized to the bare lowercase form on write
+        // ('.txt' → 'txt'); MIME-type associations pass through unchanged.
+        t.assert.deepEqual(fetched.filetype_associations, ['txt', 'image/png']);
         t.assert.equal(Boolean(fetched.maximize_on_start), true);
     },
 });