diff --git a/dlls/ntdll/nt.c b/dlls/ntdll/nt.c
index 03bf45d0a09..978919146cd 100644
--- a/dlls/ntdll/nt.c
+++ b/dlls/ntdll/nt.c
@@ -2937,6 +2937,19 @@ NTSTATUS WINAPI NtQuerySystemInformation(
             FIXME("info_class SYSTEM_INTERRUPT_INFORMATION\n");
         }
         break;
+    case SystemTimeAdjustmentInformation:
+        {
+            SYSTEM_TIME_ADJUSTMENT_QUERY query = { 156250, 156250, TRUE };
+
+            len = sizeof(query);
+            if (Length == len)
+            {
+                if (!SystemInformation) ret = STATUS_ACCESS_VIOLATION;
+                else memcpy( SystemInformation, &query, len );
+            }
+            else ret = STATUS_INFO_LENGTH_MISMATCH;
+        }
+        break;
     case SystemKernelDebuggerInformation:
         {
             SYSTEM_KERNEL_DEBUGGER_INFORMATION skdi;
diff --git a/dlls/ntdll/tests/info.c b/dlls/ntdll/tests/info.c
index 23d18b39837..f923cc7743f 100644
--- a/dlls/ntdll/tests/info.c
+++ b/dlls/ntdll/tests/info.c
@@ -23,6 +23,7 @@
 #include <stdio.h>
 
 static NTSTATUS (WINAPI * pNtQuerySystemInformation)(SYSTEM_INFORMATION_CLASS, PVOID, ULONG, PULONG);
+static NTSTATUS (WINAPI * pNtSetSystemInformation)(SYSTEM_INFORMATION_CLASS, PVOID, ULONG);
 static NTSTATUS (WINAPI * pRtlGetNativeSystemInformation)(SYSTEM_INFORMATION_CLASS, PVOID, ULONG, PULONG);
 static NTSTATUS (WINAPI * pNtQuerySystemInformationEx)(SYSTEM_INFORMATION_CLASS, void*, ULONG, void*, ULONG, ULONG*);
 static NTSTATUS (WINAPI * pNtPowerInformation)(POWER_INFORMATION_LEVEL, PVOID, ULONG, PVOID, ULONG);
@@ -76,6 +77,7 @@ static BOOL InitFunctionPtrs(void)
     }
 
     NTDLL_GET_PROC(NtQuerySystemInformation);
+    NTDLL_GET_PROC(NtSetSystemInformation);
     NTDLL_GET_PROC(RtlGetNativeSystemInformation);
     NTDLL_GET_PROC(NtPowerInformation);
     NTDLL_GET_PROC(NtQueryInformationProcess);
@@ -740,6 +742,40 @@ static void test_query_interrupt(void)
     HeapFree( GetProcessHeap(), 0, sii);
 }
 
+static void test_time_adjustment(void)
+{
+    SYSTEM_TIME_ADJUSTMENT_QUERY query;
+    SYSTEM_TIME_ADJUSTMENT adjust;
+    NTSTATUS status;
+    ULONG len;
+
+    memset( &query, 0xcc, sizeof(query) );
+    status = pNtQuerySystemInformation( SystemTimeAdjustmentInformation, &query, sizeof(query), &len );
+    ok( status == STATUS_SUCCESS, "got %08x\n", status );
+    ok( len == sizeof(query) || broken(!len) /* winxp */, "wrong len %u\n", len );
+    ok( query.TimeAdjustmentDisabled == TRUE || query.TimeAdjustmentDisabled == FALSE,
+        "wrong value %x\n", query.TimeAdjustmentDisabled );
+
+    status = pNtQuerySystemInformation( SystemTimeAdjustmentInformation, &query, sizeof(query)-1, &len );
+    ok( status == STATUS_INFO_LENGTH_MISMATCH, "got %08x\n", status );
+    ok( len == sizeof(query) || broken(!len) /* winxp */, "wrong len %u\n", len );
+
+    status = pNtQuerySystemInformation( SystemTimeAdjustmentInformation, &query, sizeof(query)+1, &len );
+    ok( status == STATUS_INFO_LENGTH_MISMATCH, "got %08x\n", status );
+    ok( len == sizeof(query) || broken(!len) /* winxp */, "wrong len %u\n", len );
+
+    adjust.TimeAdjustment = query.TimeAdjustment;
+    adjust.TimeAdjustmentDisabled = query.TimeAdjustmentDisabled;
+    status = pNtSetSystemInformation( SystemTimeAdjustmentInformation, &adjust, sizeof(adjust) );
+    ok( status == STATUS_SUCCESS || status == STATUS_PRIVILEGE_NOT_HELD, "got %08x\n", status );
+    status = pNtSetSystemInformation( SystemTimeAdjustmentInformation, &adjust, sizeof(adjust)-1 );
+    todo_wine
+    ok( status == STATUS_INFO_LENGTH_MISMATCH, "got %08x\n", status );
+    status = pNtSetSystemInformation( SystemTimeAdjustmentInformation, &adjust, sizeof(adjust)+1 );
+    todo_wine
+    ok( status == STATUS_INFO_LENGTH_MISMATCH, "got %08x\n", status );
+}
+
 static void test_query_kerndebug(void)
 {
     NTSTATUS status;
@@ -2632,6 +2668,10 @@ START_TEST(info)
     trace("Starting test_query_interrupt()\n");
     test_query_interrupt();
 
+    /* 0x1c SystemTimeAdjustmentInformation */
+    trace("Starting test_time_adjustment()\n");
+    test_time_adjustment();
+
     /* 0x23 SystemKernelDebuggerInformation */
     trace("Starting test_query_kerndebug()\n");
     test_query_kerndebug();
diff --git a/include/winternl.h b/include/winternl.h
index 14455946ba2..edcbc5ca13d 100644
--- a/include/winternl.h
+++ b/include/winternl.h
@@ -1624,6 +1624,12 @@ typedef struct _SYSTEM_REGISTRY_QUOTA_INFORMATION {
     PVOID Reserved1;
 } SYSTEM_REGISTRY_QUOTA_INFORMATION, *PSYSTEM_REGISTRY_QUOTA_INFORMATION;
 
+typedef struct _SYSTEM_TIME_ADJUSTMENT_QUERY {
+    ULONG   TimeAdjustment;
+    ULONG   TimeIncrement;
+    BOOLEAN TimeAdjustmentDisabled;
+} SYSTEM_TIME_ADJUSTMENT_QUERY, *PSYSTEM_TIME_ADJUSTMENT_QUERY;
+
 typedef struct _SYSTEM_TIME_ADJUSTMENT {
     ULONG   TimeAdjustment;
     BOOLEAN TimeAdjustmentDisabled;