What is a MUN File?

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What is MUN? Quick Facts Why Icons Moved Inside a MUN File MUN vs DLL Where MUN Files Live How to Open Getting the Icons Out Is It Safe? Good to Know FAQ

📖 What is a MUN File?

To see the system icons inside a MUN file, open it in a free ICO viewer.

A MUN file is a Windows resource file. It carries the icons and other artwork that used to live inside a system library, kept in a separate file that sits next to the library it belongs to.

The reason it exists is a change Microsoft made in Windows 10. The icons that programs pull from files like imageres.dll and shell32.dll were lifted out of those libraries and parked in matching .mun files, so the library on its own now looks almost empty.

If you have ever opened shell32.dll to grab an icon and found nothing there, this is why. The icons did not vanish, they simply moved into shell32.dll.mun, and that move is what the rest of this page explains.

⚡ Quick Facts

Full Name	Windows Resource File
Extension	.mun
Developer	Microsoft
Category	System resource file
Structure	PE, the same shape as a DLL
Holds	Icons and other resources, no code
Introduced	Windows 10 version 1903
Location	C:\Windows\SystemResources
Naming	library name plus .mun
Related Formats	DLL, MUI, ICO

📦 Why Icons Moved

For most of Windows history, a program that wanted a system icon reached into a DLL and read it straight out of the file. Version 1903 of Windows 10 split that arrangement in two.

Before 1903

imageres.dll held both the code stub and every icon in one file.

→

1903 and later

The DLL stays as a small stub, and the icons move into imageres.dll.mun.

💡 Why bother: Splitting the resources out lets Windows service and update the pictures on their own, without touching the library that uses them. Handy for Microsoft, confusing for anyone who opens the old DLL expecting to see icons.

🔬 Inside a MUN File

A MUN is not a brand new format under the hood. It borrows the same executable shape a DLL uses, then fills it with resources instead of a working program:

Executable Header

The file opens with the classic MZ header, the same signature that marks an EXE or a DLL, so tools recognise it as a Windows binary.

Resource Section

The heart of the file. Every icon, bitmap and other asset the original library published sits here in the standard resource table.

No Working Code

Unlike a real DLL, a .mun has nothing to run. It is a shell built to store and hand out resources, nothing more.

🖼️ The icons are still ICO: Each icon inside a .mun is stored in the native ICO format, the same multi size container Windows uses everywhere, so pulling one out gives you a ready to use icon file.

⚖️ MUN vs DLL

Since a .mun and its DLL are cut from the same cloth, the difference is about what each half carries after the 1903 split:

Feature	MUN	System DLL
Carries	Icons and resources	The code stub, resources removed
Runs code	No	Yes, always
Lives in	SystemResources	System32
File shape	PE binary	PE binary
Since	Windows 10 1903	Always present

✅ Good to know: This is why an icon tool aimed at the DLL finds nothing on a modern PC. Point the same tool at the paired .mun and every icon appears, since that is where they moved.

📁 Where MUN Files Live

Every .mun sits in one folder, C:\Windows\SystemResources, and each is named for the library it serves. A few carry the icons people reach for most:

MUN file	What it holds
imageres.dll.mun	Most system icons, including folders, drives and devices
shell32.dll.mun	The classic shell icon set from every Windows era
ddores.dll.mun	Hardware and device icons
wmploc.dll.mun	Media Player artwork and imagery

To see which system file owns which icon, our guide on where Windows stores its icons maps the whole set.

📂 How to Open a MUN File

Because a .mun is a resource file in DLL clothing, anything that reads DLL resources opens it. These routes all work:

✅ See Every Icon (Recommended)

Launch the Univik ICO Converter, which reads .mun files directly.
Browse to a .mun in SystemResources, such as imageres.dll.mun.
See every icon it holds at each size it offers.
Save the ones you want as ICO or PNG.

🧰 Other Tools

7-Zip: opens a .mun and exposes the .rsrc\ICON folder.
IconsExtract: the NirSoft utility lists every icon at once.
Resource Hacker: browses the resource tree in detail.
Change Icon dialog: point it at the .mun to pick an icon.

🛠️ Getting the Icons Out

Pulling icons out of a .mun works the same way it does for any resource file. The short version is load, pick, save:

📤 Save an Icon Out

Open a file such as shell32.dll.mun in the converter.
Select one icon or grab them all in one go.
Export to ICO to reuse it or PNG for design tasks.

📚 Go Deeper

Want the deeper toolkit? Our walkthrough on extracting icons from EXE and DLL files runs through 7-Zip and the NirSoft utilities with the trade offs of each. Those same steps handle a .mun, since it shares the format.

🛡️ Is It Safe?

Opening a .mun to read or copy icons out of it is completely safe, because nothing in the file runs and reading it leaves the original untouched. Editing one is where care is needed.

⚠️ Work on a copy: The files in C:\Windows\SystemResources are live system files. Changing one in place can leave Windows with missing or broken icons, and it may be reset by an update. Copy the .mun elsewhere before you touch it, and keep the original as it is.

⚠️ MUN Good to Know

🚫 The Catches

Recent only: .mun files appear from Windows 10 1903 onward.
System files: the originals are protected and best left alone.
No acronym: Microsoft has never said what MUN stands for.
Not runnable: a .mun holds resources, never a program.

✅ What MUN Is For

The real icon source: where system icons now live.
Clean extraction: icons come out as standard ICO files.
Easy to read: any DLL resource tool opens it.
Serviceable: Windows can update the artwork on its own.

❓ Frequently Asked Questions

A MUN file is a Windows resource file. Since Windows 10 version 1903, the icons and other resources that used to sit inside system DLLs were moved into matching .mun files under C:\Windows\SystemResources, so the .mun now holds the pictures the DLL once did.

Its icons were relocated. From Windows 10 version 1903 onward, imageres.dll became a small stub and its icons live in imageres.dll.mun inside C:\Windows\SystemResources. Point your tool at the .mun file and every icon shows up again.

A MUN is a resource file in the same shape as a DLL, so a tool that reads DLL resources reads it too. The Univik ICO Converter opens a .mun directly, and 7-Zip, NirSoft IconsExtract or Resource Hacker can open one as well.

Open the .mun, for example shell32.dll.mun, in an icon tool, select the icons you want and export them as ICO or PNG. The Univik ICO Converter reads the resources straight out of the file and saves each icon as its own image.

They sit in C:\Windows\SystemResources, named after the DLL they belong to. The common ones are imageres.dll.mun and shell32.dll.mun, which together hold most of the icons Windows draws for folders, drives and devices.

Reading one is safe, since opening a .mun to copy icons out changes nothing and runs no code. Editing a system .mun in place is another matter and can break Windows icons, so work on a copy rather than the original in SystemResources.

Microsoft has never spelled the acronym out in public documentation. In practice a .mun is the resource half of a system library, paired with a language neutral DLL stub that points at it, so treat it as the file that carries the resources.

It shares the DLL layout and even starts with the same header bytes, but a .mun carries only resources and runs nothing. The matching DLL in System32 was trimmed to a stub, and the icons it used to hold now live in the .mun.