diff --git a/.try.mjs b/.try.mjs
index 61b4553c..359db3f0 100644
--- a/.try.mjs
+++ b/.try.mjs
@@ -26,10 +26,24 @@ const compatDeps = {
 export default {
   scenarios: [
     {
-      name: 'ember-lts-5.8',
+      name: 'ember-lts-3.28',
       npm: {
         devDependencies: {
-          'ember-source': '~5.8.0',
+          'ember-source': '~3.28.0',
+          ...compatDeps,
+          'ember-cli': '^4.12',
+        },
+      },
+      env: {
+        ENABLE_COMPAT_BUILD: true,
+      },
+      files: compatFiles,
+    },
+    {
+      name: 'ember-lts-4.12',
+      npm: {
+        devDependencies: {
+          'ember-source': '~4.12.0',
           ...compatDeps,
         },
       },
@@ -59,6 +73,22 @@ export default {
         },
       },
     },
+    {
+      name: 'ember-lts-6.8',
+      npm: {
+        devDependencies: {
+          'ember-source': 'npm:ember-source@~6.8.0',
+        },
+      },
+    },
+    {
+      name: 'ember-lts-6.12',
+      npm: {
+        devDependencies: {
+          'ember-source': 'npm:ember-source@~6.12.0',
+        },
+      },
+    },
     {
       name: 'ember-latest',
       npm: {
diff --git a/package.json b/package.json
index f56f27de..c9efd0bd 100644
--- a/package.json
+++ b/package.json
@@ -85,7 +85,7 @@
     "eslint-plugin-ember": "^12.7.5",
     "eslint-plugin-import": "^2.32.0",
     "eslint-plugin-n": "^17.24.0",
-    "globals": "^17.4.0",
+    "globals": "^17.5.0",
     "prettier": "^3.8.2",
     "prettier-plugin-ember-template-tag": "^2.1.4",
     "publint": "^0.3.18",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 476b098b..dcda02e4 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -112,8 +112,8 @@ importers:
         specifier: ^17.24.0
         version: 17.24.0(eslint@9.39.4(jiti@2.6.1))(typescript@6.0.2)
       globals:
-        specifier: ^17.4.0
-        version: 17.4.0
+        specifier: ^17.5.0
+        version: 17.5.0
       prettier:
         specifier: ^3.8.2
         version: 3.8.2
@@ -2900,8 +2900,8 @@ packages:
     resolution: {integrity: sha512-7ACyT3wmyp3I61S4fG682L0VA2RGD9otkqGJIwNUMF1SWUombIIk+af1unuDYgMm082aHYwD+mzJvv9Iu8dsgg==}
     engines: {node: '>=18'}
 
-  globals@17.4.0:
-    resolution: {integrity: sha512-hjrNztw/VajQwOLsMNT1cbJiH2muO3OROCHnbehc8eY5JyD2gqz4AcMHPqgaOR59DjgUjYAYLeH699g/eWi2jw==}
+  globals@17.5.0:
+    resolution: {integrity: sha512-qoV+HK2yFl/366t2/Cb3+xxPUo5BuMynomoDmiaZBIdbs+0pYbjfZU+twLhGKp4uCZ/+NbtpVepH5bGCxRyy2g==}
     engines: {node: '>=18'}
 
   globalthis@1.0.4:
@@ -8558,7 +8558,7 @@ snapshots:
 
   globals@15.15.0: {}
 
-  globals@17.4.0: {}
+  globals@17.5.0: {}
 
   globalthis@1.0.4:
     dependencies:
diff --git a/src/-private/untrack.ts b/src/-private/untrack.ts
new file mode 100644
index 00000000..f6117f3a
--- /dev/null
+++ b/src/-private/untrack.ts
@@ -0,0 +1,108 @@
+import * as glimmerValidator from '@glimmer/validator';
+
+// Ember apps can provide @glimmer/validator through different module shapes
+// depending on ember-source version and bundling mode. We centralize the
+// resolution logic here so modifiers can always call a single untrack API.
+
+type UntrackCallback = () => void;
+type Untrack = (callback: UntrackCallback) => void;
+type ValidatorRequire = (moduleName: string) => ValidatorModule;
+
+interface ValidatorModule {
+  untrack?: unknown;
+  beginUntrackFrame?: unknown;
+  endUntrackFrame?: unknown;
+}
+
+function getCallable<T extends (...args: never[]) => unknown>(
+  target: unknown,
+  property: string,
+): T | undefined {
+  const value = (target as Record<string, unknown>)[property];
+
+  return typeof value === 'function' ? (value as T) : undefined;
+}
+
+function tryRequire(maybeRequire: ValidatorRequire | undefined) {
+  if (typeof maybeRequire !== 'function') {
+    return undefined;
+  }
+
+  try {
+    return maybeRequire('@glimmer/validator');
+  } catch {
+    return undefined;
+  }
+}
+
+function resolveValidatorModule(): ValidatorModule {
+  const importedModule = glimmerValidator as ValidatorModule;
+  const importedUntrack = getCallable<Untrack>(importedModule, 'untrack');
+  const importedBeginUntrackFrame = getCallable<() => void>(
+    importedModule,
+    'beginUntrackFrame',
+  );
+
+  if (importedUntrack || importedBeginUntrackFrame) {
+    // Modern ESM shape: use the imported namespace directly.
+    return importedModule;
+  }
+
+  const globalWithEmber = globalThis as {
+    Ember?: {
+      __loader?: {
+        require?: (moduleName: string) => ValidatorModule;
+      };
+    };
+    require?: ValidatorRequire;
+    requirejs?: ValidatorRequire;
+  };
+
+  const requireCandidates: Array<ValidatorRequire | undefined> = [
+    globalWithEmber.Ember?.__loader?.require,
+    globalWithEmber.require,
+    globalWithEmber.requirejs,
+  ];
+
+  for (const maybeRequire of requireCandidates) {
+    const module = tryRequire(maybeRequire);
+
+    if (module) {
+      // Older or compat builds: resolve from runtime module loader.
+      return module;
+    }
+  }
+
+  return {};
+}
+
+export const untrack: Untrack = (() => {
+  const validator = resolveValidatorModule();
+  const moduleUntrack = getCallable<Untrack>(validator, 'untrack');
+
+  if (moduleUntrack) {
+    return moduleUntrack;
+  }
+
+  const beginUntrackFrame = getCallable<() => void>(
+    validator,
+    'beginUntrackFrame',
+  );
+  const endUntrackFrame = getCallable<() => void>(validator, 'endUntrackFrame');
+
+  if (beginUntrackFrame && endUntrackFrame) {
+    // Some validator versions expose frame primitives instead of untrack.
+    return (callback: UntrackCallback) => {
+      beginUntrackFrame();
+
+      try {
+        callback();
+      } finally {
+        endUntrackFrame();
+      }
+    };
+  }
+
+  // Last resort for very old or unexpected runtime shapes.
+  return (callback: UntrackCallback) => callback();
+})();
diff --git a/src/modifiers/did-update.ts b/src/modifiers/did-update.ts
index 298f7a3b..a65143ba 100644
--- a/src/modifiers/did-update.ts
+++ b/src/modifiers/did-update.ts
@@ -1,5 +1,5 @@
 import { setModifierManager, capabilities } from '@ember/modifier';
-import { untrack } from '@glimmer/validator';
+import { untrack } from '../-private/untrack.ts';
 
 import type {
   ModifierArgs,