diff --git a/api/core/workflow/constants.py b/api/core/workflow/constants.py
index e3fe17c284..0fad43d0f6 100644
--- a/api/core/workflow/constants.py
+++ b/api/core/workflow/constants.py
@@ -1,3 +1,5 @@
 SYSTEM_VARIABLE_NODE_ID = "sys"
 ENVIRONMENT_VARIABLE_NODE_ID = "env"
 CONVERSATION_VARIABLE_NODE_ID = "conversation"
+MEMORY_BLOCK_VARIABLE_NODE_ID = "memory_block"
+