diff --git a/reactos/subsystems/win32/win32k/ntuser/ntuser.c b/reactos/subsystems/win32/win32k/ntuser/ntuser.c
index 0ddba1eb5bc..7f5e95b194a 100644
--- a/reactos/subsystems/win32/win32k/ntuser/ntuser.c
+++ b/reactos/subsystems/win32/win32k/ntuser/ntuser.c
@@ -82,15 +82,18 @@ VOID FASTCALL CleanupUserImpl(VOID)
 
 VOID FASTCALL UserEnterShared(VOID)
 {
+   KeEnterCriticalRegion();
    ExAcquireResourceSharedLite(&UserLock, TRUE);
 }
 
 VOID FASTCALL UserEnterExclusive(VOID)
 {
+   KeEnterCriticalRegion();
    ExAcquireResourceExclusiveLite(&UserLock, TRUE);
 }
 
 VOID FASTCALL UserLeave(VOID)
 {
    ExReleaseResourceLite(&UserLock);
+   KeLeaveCriticalRegion();
 }