diff --git a/ntoskrnl/fsrtl/name.c b/ntoskrnl/fsrtl/name.c
index fef798cc86d..a6f0c004b7f 100644
--- a/ntoskrnl/fsrtl/name.c
+++ b/ntoskrnl/fsrtl/name.c
@@ -143,7 +143,7 @@ FsRtlIsNameInExpressionPrivate(IN PUNICODE_STRING Expression,
                     ASSERT((OldBackTracking == BackTrackingBuffer) || (OldBackTracking == OldBackTrackingBuffer));
 
                     /* Calculate buffer size */
-                    BackTrackingBufferSize = (Expression->Length + 1) * 2;
+                    BackTrackingBufferSize = Expression->Length + 1;
 
                     /* Allocate memory for both back-tracking buffers */
                     AllocatedBuffer = ExAllocatePoolWithTag(PagedPool | POOL_RAISE_IF_ALLOCATION_FAILURE,