diff --git a/hugvey/story.py b/hugvey/story.py
index e84d50e..9d411b4 100644
--- a/hugvey/story.py
+++ b/hugvey/story.py
@@ -1275,6 +1275,7 @@ class Story(object):
         self.interruptionDiversions = []
         self.variables = {}
         self.variableValues = {}  # captured variables from replies
+        self.runId = uuid.uuid4().hex
 
     def pause(self):
         self.logger.debug('pause hugvey')
@@ -1314,7 +1315,7 @@ class Story(object):
             
         self.variableValues[name] = value
         if store:
-            self.hugvey.command.variableStore.addVariable(name, value, self.hugvey.id, self.language_code)
+            self.hugvey.command.variableStore.addVariable(self.runId, name, value, self.hugvey.id, self.language_code)
 
         if name not in self.variables:
             return
@@ -1397,6 +1398,7 @@ class Story(object):
         self.lastSpeechEndTime = None
         self.variableValues = {}  # captured variables from replies
         self.finish_time = False
+        self.runId = uuid.uuid4().hex
 
         self.events = []  # queue of received events
         self.commands = []  # queue of commands to send
diff --git a/hugvey/variablestore.py b/hugvey/variablestore.py
index 1f6c0c5..c4d8c1f 100644
--- a/hugvey/variablestore.py
+++ b/hugvey/variablestore.py
@@ -8,11 +8,12 @@ logger = mainLogger.getChild("variableStore")
 
 
 class Variable:
-    def __init__(self, name: str, value: str, hugveyId: int, languageCode: str):
+    def __init__(self, name: str, value: str, hugveyId: int, languageCode: str, runId: str):
         self.name = name
         self.value = value
         self.hugveyId = hugveyId
         self.languageCode = languageCode
+        self.runId = runId
 
 class VariableStore:
     def __init__(self, db_filename):
@@ -21,6 +22,7 @@ class VariableStore:
         # make sure the table exits.
         createSqls = ["""
         CREATE TABLE IF NOT EXISTS `variables` (
+            `run_id`    VARCHAR(32),
             `name`    VARCHAR(255),
             `hugvey`    INTEGER,
             `language_code` VARCHAR(100),
@@ -34,6 +36,12 @@ class VariableStore:
             `name`,
             `createdAt`    DESC
         );
+        """,
+        """
+        CREATE UNIQUE INDEX IF NOT EXISTS `unique_per_run` ON `variables` (
+            `run_id`,
+            `name`
+        );
         """]
         cur = self.conn.cursor()
         for sql in createSqls:
@@ -41,17 +49,18 @@ class VariableStore:
         self.conn.commit()
         self.q = asyncio.Queue()
     
-    def addVariable(self, name, value, hugveyId, languageCode):
-        logger.debug(f"Queing storing of {name} for {hugveyId} ({languageCode})")
-        self.q.put_nowait(Variable(name, value, hugveyId, languageCode))
+    def addVariable(self, runId, name, value, hugveyId, languageCode):
+        logger.debug(f"Queing storing of {name} for {hugveyId} ({languageCode}) - run {runId}")
+        self.q.put_nowait(Variable(name, value, hugveyId, languageCode, runId))
     
     async def queueProcessor(self):
         while True:
             #: :var v: Variable
             v = await self.q.get()
             c = self.conn.cursor()
-            logger.info(f"Store variable {v.name} for {v.hugveyId} ({v.languageCode}): '{v.value}'")
-            c.execute("INSERT INTO variables (name, hugvey, language_code, createdAt, val) VALUES (?,?, ?, current_timestamp,?)", (v.name, v.hugveyId, v.languageCode, v.value))
+            logger.info(f"Store variable {v.name} for {v.hugveyId} ({v.languageCode}): '{v.value}' - run {v.runId}")
+            # use runId to update, rather than insert a variable for the same run.
+            c.execute("INSERT OR REPLACE INTO variables (run_id, name, hugvey, language_code, createdAt, val) VALUES (?,?,?, ?, current_timestamp,?)", (v.runId,v.name, v.hugveyId, v.languageCode, v.value))
             self.conn.commit()
             c.close()