diff --git a/src/talemate/agents/world_state/websocket_handler.py b/src/talemate/agents/world_state/websocket_handler.py
index d028cddc..b40f2091 100644
--- a/src/talemate/agents/world_state/websocket_handler.py
+++ b/src/talemate/agents/world_state/websocket_handler.py
@@ -3,7 +3,6 @@ import pydantic
 from talemate.instance import get_agent
 from talemate.server.websocket_plugin import Plugin
 from talemate.status import set_loading
-from talemate.util.time import amount_unit_to_iso8601_duration
 
 __all__ = [
     "WorldStateWebsocketHandler",
@@ -19,24 +18,6 @@ class SummarizeAndPinPayload(pydantic.BaseModel):
     num_messages: int = 5
 
 
-class AdvanceTimePayload(pydantic.BaseModel):
-    duration: str | None = None
-    amount: int | None = None
-    unit: str | None = None
-
-    @pydantic.model_validator(mode="after")
-    def check_duration_or_amount_unit(self):
-        if not self.duration and (self.amount is None or not self.unit):
-            raise ValueError("Either 'duration' or 'amount' + 'unit' must be provided.")
-        return self
-
-    @property
-    def iso_duration(self) -> str:
-        if self.duration:
-            return self.duration
-        return amount_unit_to_iso8601_duration(self.amount, self.unit)
-
-
 class WorldStateWebsocketHandler(Plugin):
     router = "world_state_agent"
 
@@ -66,9 +47,3 @@ class WorldStateWebsocketHandler(Plugin):
             message_id, num_messages=payload.num_messages
         )
         await self.signal_operation_done(allow_auto_save=False)
-
-    @set_loading("Advancing time", cancellable=True, as_async=True)
-    async def handle_advance_time(self, data: dict):
-        payload = AdvanceTimePayload(**data)
-        await self.agent.advance_time(payload.iso_duration)
-        await self.signal_operation_done()
diff --git a/talemate_frontend/src/components/SceneToolsTime.vue b/talemate_frontend/src/components/SceneToolsTime.vue
index a9a8620d..88264950 100644
--- a/talemate_frontend/src/components/SceneToolsTime.vue
+++ b/talemate_frontend/src/components/SceneToolsTime.vue
@@ -139,13 +139,21 @@ export default {
             this.customTimeDialog = true;
         },
 
+        amountUnitToIso8601(amount, unit) {
+            const n = Math.abs(amount);
+            switch (unit) {
+                case 'minutes': return `PT${n}M`;
+                case 'hours':   return `PT${n}H`;
+                case 'days':    return `P${n}D`;
+                case 'weeks':   return `P${n}W`;
+                case 'months':  return `P${n}M`;
+                case 'years':   return `P${n}Y`;
+                default: throw new Error(`Invalid unit: ${unit}`);
+            }
+        },
+
         submitCustomTime() {
-            this.getWebsocket().send(JSON.stringify({
-                type: 'world_state_agent',
-                action: 'advance_time',
-                amount: this.customTimeAmount,
-                unit: this.customTimeUnit,
-            }));
+            this.advanceTime(this.amountUnitToIso8601(this.customTimeAmount, this.customTimeUnit));
             this.customTimeDialog = false;
         },
     },