diff --git a/dlls/kernel/sync.c b/dlls/kernel/sync.c
index bd4cc7213b..938144c039 100644
--- a/dlls/kernel/sync.c
+++ b/dlls/kernel/sync.c
@@ -1641,31 +1641,32 @@ BOOL WINAPI GetMailslotInfo( HANDLE hMailslot, LPDWORD lpMaxMessageSize,
                                LPDWORD lpNextSize, LPDWORD lpMessageCount,
                                LPDWORD lpReadTimeout )
 {
-    BOOL r;
+    FILE_MAILSLOT_QUERY_INFORMATION info;
+    IO_STATUS_BLOCK iosb;
+    NTSTATUS status;
 
-    TRACE("%p %p %p %p %p\n",hMailslot,
-          lpMaxMessageSize,lpNextSize,lpMessageCount,lpReadTimeout);
+    TRACE("%p %p %p %p %p\n",hMailslot, lpMaxMessageSize,
+          lpNextSize, lpMessageCount, lpReadTimeout);
 
-    SERVER_START_REQ( set_mailslot_info )
+    status = NtQueryInformationFile( hMailslot, &iosb, &info, sizeof info,
+                                     FileMailslotQueryInformation );
+
+    if( status != STATUS_SUCCESS )
     {
-        req->handle = hMailslot;
-        req->flags = 0;
-        r = !wine_server_call_err( req );
-        if( r )
-        {
-            if( lpMaxMessageSize )
-                *lpMaxMessageSize = reply->max_msgsize;
-            if( lpNextSize )
-                *lpNextSize = reply->next_msgsize;
-            if( lpMessageCount )
-                *lpMessageCount = reply->msg_count;
-            if( lpReadTimeout )
-                *lpReadTimeout = reply->read_timeout;
-        }
+        SetLastError( RtlNtStatusToDosError(status) );
+        return FALSE;
     }
-    SERVER_END_REQ;
 
-    return r;
+    if( lpMaxMessageSize )
+        *lpMaxMessageSize = info.MaximumMessageSize;
+    if( lpNextSize )
+        *lpNextSize = info.NextMessageSize;
+    if( lpMessageCount )
+        *lpMessageCount = info.MessagesAvailable;
+    if( lpReadTimeout )
+        *lpReadTimeout = info.ReadTimeout.QuadPart / -10000;
+
+    return TRUE;
 }
 
 
@@ -1684,20 +1685,21 @@ BOOL WINAPI GetMailslotInfo( HANDLE hMailslot, LPDWORD lpMaxMessageSize,
  */
 BOOL WINAPI SetMailslotInfo( HANDLE hMailslot, DWORD dwReadTimeout)
 {
-    BOOL r;
+    FILE_MAILSLOT_SET_INFORMATION info;
+    IO_STATUS_BLOCK iosb;
+    NTSTATUS status;
 
     TRACE("%p %ld\n", hMailslot, dwReadTimeout);
 
-    SERVER_START_REQ( set_mailslot_info )
+    info.ReadTimeout.QuadPart = dwReadTimeout * -10000;
+    status = NtSetInformationFile( hMailslot, &iosb, &info, sizeof info,
+                                   FileMailslotSetInformation );
+    if( status != STATUS_SUCCESS )
     {
-        req->handle = hMailslot;
-        req->flags = MAILSLOT_SET_READ_TIMEOUT;
-        req->read_timeout = dwReadTimeout;
-        r = !wine_server_call_err( req );
+        SetLastError( RtlNtStatusToDosError(status) );
+        return FALSE;
     }
-    SERVER_END_REQ;
-
-    return r;
+    return TRUE;
 }
 
 
diff --git a/dlls/ntdll/file.c b/dlls/ntdll/file.c
index 92c1bf6480..705bbb1d01 100644
--- a/dlls/ntdll/file.c
+++ b/dlls/ntdll/file.c
@@ -941,7 +941,7 @@ NTSTATUS WINAPI NtQueryInformationFile( HANDLE hFile, PIO_STATUS_BLOCK io,
         0,                                             /* FilePipeInformation */
         0,                                             /* FilePipeLocalInformation */
         0,                                             /* FilePipeRemoteInformation */
-        0,                                             /* FileMailslotQueryInformation */
+        sizeof(FILE_MAILSLOT_QUERY_INFORMATION),       /* FileMailslotQueryInformation */
         0,                                             /* FileMailslotSetInformation */
         0,                                             /* FileCompressionInformation */
         0,                                             /* FileObjectIdInformation */
@@ -1093,6 +1093,27 @@ NTSTATUS WINAPI NtQueryInformationFile( HANDLE hFile, PIO_STATUS_BLOCK io,
             }
         }
         break;
+    case FileMailslotQueryInformation:
+        {
+            FILE_MAILSLOT_QUERY_INFORMATION *info = ptr;
+
+            SERVER_START_REQ( set_mailslot_info )
+            {
+                req->handle = hFile;
+                req->flags = 0;
+                io->u.Status = wine_server_call( req );
+                if( io->u.Status == STATUS_SUCCESS )
+                {
+                    info->MaximumMessageSize = reply->max_msgsize;
+                    info->MailslotQuota = 0;
+                    info->NextMessageSize = reply->next_msgsize;
+                    info->MessagesAvailable = reply->msg_count;
+                    info->ReadTimeout.QuadPart = reply->read_timeout * -10000;
+                }
+            }
+            SERVER_END_REQ;
+        }
+        break;
     default:
         FIXME("Unsupported class (%d)\n", class);
         io->u.Status = STATUS_NOT_IMPLEMENTED;
@@ -1229,6 +1250,21 @@ NTSTATUS WINAPI NtSetInformationFile(HANDLE handle, PIO_STATUS_BLOCK io,
         else io->u.Status = STATUS_INVALID_PARAMETER_3;
         break;
 
+    case FileMailslotSetInformation:
+        {
+            FILE_MAILSLOT_SET_INFORMATION *info = ptr;
+
+            SERVER_START_REQ( set_mailslot_info )
+            {
+                req->handle = handle;
+                req->flags = MAILSLOT_SET_READ_TIMEOUT;
+                req->read_timeout = info->ReadTimeout.QuadPart / -10000;
+                io->u.Status = wine_server_call( req );
+            }
+            SERVER_END_REQ;
+        }
+        break;
+
     default:
         FIXME("Unsupported class (%d)\n", class);
         io->u.Status = STATUS_NOT_IMPLEMENTED;
diff --git a/include/winternl.h b/include/winternl.h
index 9deca751e4..6e22f8f9e7 100644
--- a/include/winternl.h
+++ b/include/winternl.h
@@ -436,6 +436,18 @@ typedef struct _FILE_ATTRIBUTE_TAG_INFORMATION
     ULONG ReparseTag;
 } FILE_ATTRIBUTE_TAG_INFORMATION, *PFILE_ATTRIBUTE_TAG_INFORMATION;
 
+typedef struct _FILE_MAILSLOT_QUERY_INFORMATION {
+    ULONG MaximumMessageSize;
+    ULONG MailslotQuota;
+    ULONG NextMessageSize;
+    ULONG MessagesAvailable;
+    LARGE_INTEGER ReadTimeout;
+} FILE_MAILSLOT_QUERY_INFORMATION, *PFILE_MAILSLOT_QUERY_INFORMATION;
+
+typedef struct _FILE_MAILSLOT_SET_INFORMATION {
+    LARGE_INTEGER ReadTimeout;
+} FILE_MAILSLOT_SET_INFORMATION, *PFILE_MAILSLOT_SET_INFORMATION;
+
 typedef struct _FILE_ALL_INFORMATION
 {
     FILE_BASIC_INFORMATION     BasicInformation;