diff --git a/library/std/src/sys/windows/c/windows_sys.lst b/library/std/src/sys/windows/c/windows_sys.lst
index 631aedd26b4ea..f73d202a777ca 100644
--- a/library/std/src/sys/windows/c/windows_sys.lst
+++ b/library/std/src/sys/windows/c/windows_sys.lst
@@ -2477,11 +2477,11 @@ Windows.Win32.System.Pipes.PIPE_TYPE_BYTE
 Windows.Win32.System.Pipes.PIPE_TYPE_MESSAGE
 Windows.Win32.System.Pipes.PIPE_WAIT
 Windows.Win32.System.SystemInformation.GetSystemDirectoryW
-Windows.Win32.System.SystemInformation.GetSystemInfo
 Windows.Win32.System.SystemInformation.GetSystemTimeAsFileTime
 Windows.Win32.System.SystemInformation.GetWindowsDirectoryW
 Windows.Win32.System.SystemInformation.PROCESSOR_ARCHITECTURE
 Windows.Win32.System.SystemInformation.SYSTEM_INFO
+Windows.Win32.System.SystemServices.ALL_PROCESSOR_GROUPS
 Windows.Win32.System.SystemServices.DLL_PROCESS_DETACH
 Windows.Win32.System.SystemServices.DLL_THREAD_DETACH
 Windows.Win32.System.SystemServices.EXCEPTION_MAXIMUM_PARAMETERS
@@ -2513,6 +2513,7 @@ Windows.Win32.System.Threading.DEBUG_PROCESS
 Windows.Win32.System.Threading.DETACHED_PROCESS
 Windows.Win32.System.Threading.ExitProcess
 Windows.Win32.System.Threading.EXTENDED_STARTUPINFO_PRESENT
+Windows.Win32.System.Threading.GetActiveProcessorCount
 Windows.Win32.System.Threading.GetCurrentProcess
 Windows.Win32.System.Threading.GetCurrentProcessId
 Windows.Win32.System.Threading.GetCurrentThread
diff --git a/library/std/src/sys/windows/c/windows_sys.rs b/library/std/src/sys/windows/c/windows_sys.rs
index 02377087173a7..ed5102c4b5c52 100644
--- a/library/std/src/sys/windows/c/windows_sys.rs
+++ b/library/std/src/sys/windows/c/windows_sys.rs
@@ -219,6 +219,10 @@ extern "system" {
     pub fn FreeEnvironmentStringsW(penv: PCWSTR) -> BOOL;
 }
 #[link(name = "kernel32")]
+extern "system" {
+    pub fn GetActiveProcessorCount(groupnumber: u16) -> u32;
+}
+#[link(name = "kernel32")]
 extern "system" {
     pub fn GetCommandLineW() -> PCWSTR;
 }
@@ -338,10 +342,6 @@ extern "system" {
     pub fn GetSystemDirectoryW(lpbuffer: PWSTR, usize: u32) -> u32;
 }
 #[link(name = "kernel32")]
-extern "system" {
-    pub fn GetSystemInfo(lpsysteminfo: *mut SYSTEM_INFO) -> ();
-}
-#[link(name = "kernel32")]
 extern "system" {
     pub fn GetSystemTimeAsFileTime(lpsystemtimeasfiletime: *mut FILETIME) -> ();
 }
@@ -822,6 +822,7 @@ impl ::core::clone::Clone for ADDRINFOA {
 pub const AF_INET: ADDRESS_FAMILY = 2u16;
 pub const AF_INET6: ADDRESS_FAMILY = 23u16;
 pub const AF_UNSPEC: ADDRESS_FAMILY = 0u16;
+pub const ALL_PROCESSOR_GROUPS: u32 = 65535u32;
 #[repr(C)]
 pub union ARM64_NT_NEON128 {
     pub Anonymous: ARM64_NT_NEON128_0,
diff --git a/library/std/src/sys/windows/thread.rs b/library/std/src/sys/windows/thread.rs
index 18cecb65681d2..cb52404a03010 100644
--- a/library/std/src/sys/windows/thread.rs
+++ b/library/std/src/sys/windows/thread.rs
@@ -101,15 +101,13 @@ impl Thread {
 
 pub fn available_parallelism() -> io::Result<NonZeroUsize> {
     let res = unsafe {
-        let mut sysinfo: c::SYSTEM_INFO = crate::mem::zeroed();
-        c::GetSystemInfo(&mut sysinfo);
-        sysinfo.dwNumberOfProcessors as usize
+        // FIXME: windows::Win32::System::SystemServices::ALL_PROCESSOR_GROUPS should be u16, not u32
+        // FIXME: if you need even more accurate result on 32-bit Windows with more, than 64 cores,
+        // consider implementing this using GetLogicalProcessorInformationEx
+        c::GetActiveProcessorCount(c::ALL_PROCESSOR_GROUPS as u16) as usize
     };
     match res {
-        0 => Err(io::const_io_error!(
-            io::ErrorKind::NotFound,
-            "The number of hardware threads is not known for the target platform",
-        )),
+        0 => Err(io::Error::last_os_error()),
         cpus => Ok(unsafe { NonZeroUsize::new_unchecked(cpus) }),
     }
 }
diff --git a/src/tools/miri/src/shims/windows/foreign_items.rs b/src/tools/miri/src/shims/windows/foreign_items.rs
index cb90ed57ffe99..ba55b04ca6867 100644
--- a/src/tools/miri/src/shims/windows/foreign_items.rs
+++ b/src/tools/miri/src/shims/windows/foreign_items.rs
@@ -203,6 +203,16 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 )?;
             }
 
+            // Number of cores, but more accurate vaulue, than GetSystemInfo.dwNumberOfProcessors
+            // if number of cores > 64. If called with ALL_PROCESSOR_GROUPS as groupnumber,
+            // returns total number of cores, instead of number in group, see
+            // https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-getactiveprocessorcount
+            "GetActiveProcessorCount" => {
+                let [groupnumber] = this.check_shim(abi, Abi::System { unwind: false }, link_name, args)?;
+                this.read_scalar(groupnumber)?.to_u16()?;
+                this.write_scalar(Scalar::from_u32(this.machine.num_cpus), dest)?;
+            }
+
             // Thread-local storage
             "TlsAlloc" => {
                 // This just creates a key; Windows does not natively support TLS destructors.