diff --git a/monkey/common/agent_events/abstract_agent_event.py b/monkey/common/agent_events/abstract_agent_event.py
index b7719d03e..8c3655602 100644
--- a/monkey/common/agent_events/abstract_agent_event.py
+++ b/monkey/common/agent_events/abstract_agent_event.py
@@ -24,7 +24,7 @@ class AbstractAgentEvent(InfectionMonkeyBaseModel, ABC):
         :param tags: The set of tags associated with the event
     """
 
-    source: AgentID = Field(default=None)
+    source: AgentID
     target: Union[MachineID, IPv4Address, None] = Field(default=None)
     timestamp: float = Field(default_factory=time.time)
     tags: FrozenSet[str] = Field(default_factory=frozenset)