diff --git a/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.c b/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.c
index de0a32ee87..c8ee79a1ec 100644
--- a/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.c
+++ b/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.c
@@ -431,7 +431,7 @@ SmmVariableHandler (
     return EFI_SUCCESS;
   }
 
-  if (*CommBufferSize < sizeof(SMM_VARIABLE_COMMUNICATE_HEADER) - 1) {
+  if (*CommBufferSize < SMM_VARIABLE_COMMUNICATE_HEADER_SIZE) {
     return EFI_SUCCESS;
   }