Error: 'non standard syntax, use & to create pointer to member'

I’m trying to use EnumWindows to list all the window titles of other apps, but getting the error:

'non-standard syntax; use '&' to create a pointer to member

Here’s my code:

void ofApp::setup(){
	
	EnumWindows(WorkerProc, NULL);

}

BOOL CALLBACK WorkerProc(HWND hwnd, LPARAM lParam) {
	static TCHAR buffer[50];
	
	GetWindowText(hwnd, buffer, 50);
	if (_tcsstr(buffer, L"Desired Window")) {
		// do something with hwnd here
		return FALSE;
	}

	return TRUE;
}

and here’s how it’s defined in ofApp.h:

BOOL CALLBACK WorkerProc(HWND hwnd, LPARAM lParam);

Any ideas? Is it really just missing an ‘&’ somewhere?
My understanding of pointers is lacking…