diff --git a/src/internal/syscall/windows/registry/key.go b/src/internal/syscall/windows/registry/key.go
index ba5c292c5e..ec38cf9288 100644
--- a/src/internal/syscall/windows/registry/key.go
+++ b/src/internal/syscall/windows/registry/key.go
@@ -25,7 +25,10 @@
 //
 package registry
 
-import "syscall"
+import (
+	"runtime"
+	"syscall"
+)
 
 const (
 	// Registry key security and access rights.
@@ -88,6 +91,12 @@ func OpenKey(k Key, path string, access uint32) (Key, error) {
 
 // ReadSubKeyNames returns the names of subkeys of key k.
 func (k Key) ReadSubKeyNames() ([]string, error) {
+	// RegEnumKeyEx must be called repeatedly and to completion.
+	// During this time, this goroutine cannot migrate away from
+	// its current thread. See #49320.
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
 	names := make([]string, 0)
 	// Registry key size limit is 255 bytes and described there:
 	// https://msdn.microsoft.com/library/windows/desktop/ms724872.aspx
diff --git a/src/syscall/syscall_windows.go b/src/syscall/syscall_windows.go
index 48fedb33d7..69e163e00f 100644
--- a/src/syscall/syscall_windows.go
+++ b/src/syscall/syscall_windows.go
@@ -279,7 +279,7 @@ func NewCallbackCDecl(fn interface{}) uintptr {
 //sys	RegOpenKeyEx(key Handle, subkey *uint16, options uint32, desiredAccess uint32, result *Handle) (regerrno error) = advapi32.RegOpenKeyExW
 //sys	RegCloseKey(key Handle) (regerrno error) = advapi32.RegCloseKey
 //sys	RegQueryInfoKey(key Handle, class *uint16, classLen *uint32, reserved *uint32, subkeysLen *uint32, maxSubkeyLen *uint32, maxClassLen *uint32, valuesLen *uint32, maxValueNameLen *uint32, maxValueLen *uint32, saLen *uint32, lastWriteTime *Filetime) (regerrno error) = advapi32.RegQueryInfoKeyW
-//sys	RegEnumKeyEx(key Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, class *uint16, classLen *uint32, lastWriteTime *Filetime) (regerrno error) = advapi32.RegEnumKeyExW
+//sys	regEnumKeyEx(key Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, class *uint16, classLen *uint32, lastWriteTime *Filetime) (regerrno error) = advapi32.RegEnumKeyExW
 //sys	RegQueryValueEx(key Handle, name *uint16, reserved *uint32, valtype *uint32, buf *byte, buflen *uint32) (regerrno error) = advapi32.RegQueryValueExW
 //sys	getCurrentProcessId() (pid uint32) = kernel32.GetCurrentProcessId
 //sys	GetConsoleMode(console Handle, mode *uint32) (err error) = kernel32.GetConsoleMode
@@ -1301,3 +1301,31 @@ func newProcThreadAttributeList(maxAttrCount uint32) (*_PROC_THREAD_ATTRIBUTE_LI
 	}
 	return al, nil
 }
+
+// RegEnumKeyEx enumerates the subkeys of an open registry key.
+// Each call retrieves information about one subkey. name is
+// a buffer that should be large enough to hold the name of the
+// subkey plus a null terminating character. nameLen is its
+// length. On return, nameLen will contain the actual length of the
+// subkey.
+//
+// Should name not be large enough to hold the subkey, this function
+// will return ERROR_MORE_DATA, and must be called again with an
+// appropriately sized buffer.
+//
+// reserved must be nil. class and classLen behave like name and nameLen
+// but for the class of the subkey, except that they are optional.
+// lastWriteTime, if not nil, will be populated with the time the subkey
+// was last written.
+//
+// The caller must enumerate all subkeys in order. That is
+// RegEnumKeyEx must be called with index starting at 0, incrementing
+// the index until the function returns ERROR_NO_MORE_ITEMS, or with
+// the index of the last subkey (obtainable from RegQueryInfoKey),
+// decrementing until index 0 is enumerated.
+//
+// Successive calls to this API must happen on the same OS thread,
+// so call runtime.LockOSThread before calling this function.
+func RegEnumKeyEx(key Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, class *uint16, classLen *uint32, lastWriteTime *Filetime) (regerrno error) {
+	return regEnumKeyEx(key, index, name, nameLen, reserved, class, classLen, lastWriteTime)
+}
diff --git a/src/syscall/zsyscall_windows.go b/src/syscall/zsyscall_windows.go
index 7bfff16be6..2d6f34e059 100644
--- a/src/syscall/zsyscall_windows.go
+++ b/src/syscall/zsyscall_windows.go
@@ -305,7 +305,7 @@ func RegCloseKey(key Handle) (regerrno error) {
 	return
 }
 
-func RegEnumKeyEx(key Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, class *uint16, classLen *uint32, lastWriteTime *Filetime) (regerrno error) {
+func regEnumKeyEx(key Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, class *uint16, classLen *uint32, lastWriteTime *Filetime) (regerrno error) {
 	r0, _, _ := Syscall9(procRegEnumKeyExW.Addr(), 8, uintptr(key), uintptr(index), uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(nameLen)), uintptr(unsafe.Pointer(reserved)), uintptr(unsafe.Pointer(class)), uintptr(unsafe.Pointer(classLen)), uintptr(unsafe.Pointer(lastWriteTime)), 0)
 	if r0 != 0 {
 		regerrno = Errno(r0)