Download the latest Windows Defender updates for your PC:

For a 32-bit system | For a 64-bit system | For Windows RT
How to determine whether your computer is running a 32-bit version or 64-bit version of Windows

You can install the definition file immediately, or save it to your PC first.

• Tap or click Run to install the definition file immediately.
• Tap or click Save to save the file to your PC. Make sure you remember the name of the folder where you save the file.

To install the definition updates from a saved file:

1. Use the Search charm on the Start screen to locate the folder where you saved the definition file.
2. Run the file:
   • If you're running a 32-bit or 64-bit version of Windows, press and hold (or right-click) mpam-fe.exe, tap or click Run as administrator, and then tap or click Run. You might be asked for an admin password or to confirm your choice.
   • If you're running Windows RT, press and hold (or right-click) mpam-fe.exe, tap or click Run as administrator, and then tap or click Run. You might be asked for an admin password or to confirm your choice.

Note: If you don't have an administrator account on the computer, ask an admin to sign in and install the definition file for you.

To download the latest Windows Defender updates for your PC:

For a 32-bit system | For a 64-bit system
How to determine whether your computer is running a 32-bit version or 64-bit version of Windows

You can install the definition file immediately, or save it to your PC first.

• Click Run to install the definition file immediately.
• Click Save to save the file to your PC. Make sure you remember the name of the folder where you save the file.

To install the definition updates from a saved file:

1. Click Start, click Documents, and then locate the folder where you saved the definition file.
2. Right-click mpas-fe.exe, click Run as administrator, and click Run. You might be asked for an admin password or to confirm your choice.

Note: If you don't have an administrator account on the PC, ask an admin to sign in and install the definition file for you.

Additional resources:

• Windows Defender website
• Support for Windows Defender
• Windows Defender in Microsoft Answers