diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c
index f11300b96a..0a6c872baa 100644
--- a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c
+++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c
@@ -513,6 +513,10 @@ SmmVariableHandler (
       break;
 
     case SMM_VARIABLE_FUNCTION_READY_TO_BOOT:
+      if (AtRuntime()) {
+        Status = EFI_UNSUPPORTED;
+        break;
+      }
       ReclaimForOS ();
       Status = EFI_SUCCESS;
       break;
diff --git a/SecurityPkg/VariableAuthenticated/RuntimeDxe/Variable.c b/SecurityPkg/VariableAuthenticated/RuntimeDxe/Variable.c
index fe7d5b9352..bae5f7bc45 100644
--- a/SecurityPkg/VariableAuthenticated/RuntimeDxe/Variable.c
+++ b/SecurityPkg/VariableAuthenticated/RuntimeDxe/Variable.c
@@ -2528,8 +2528,8 @@ VariableServiceQueryVariableInfo (
 /**
   This function reclaims variable storage if free size is below the threshold.
 
-  Caution: This function may be invoked at SMM runtime.
-  Care must be taken to make sure not security issue at runtime.
+  Caution: This function may be invoked at SMM mode.
+  Care must be taken to make sure not security issue.
 
 **/
 VOID
diff --git a/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.c b/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.c
index 8247836a63..de0a32ee87 100644
--- a/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.c
+++ b/SecurityPkg/VariableAuthenticated/RuntimeDxe/VariableSmm.c
@@ -519,6 +519,10 @@ SmmVariableHandler (
       break;
 
     case SMM_VARIABLE_FUNCTION_READY_TO_BOOT:
+      if (AtRuntime()) {
+        Status = EFI_UNSUPPORTED;
+        break;
+      }
       ReclaimForOS ();
       Status = EFI_SUCCESS;
       break;