diff --git a/src/c3nav/mesh/api.py b/src/c3nav/mesh/api.py
index dfd65fab..a7f985da 100644
--- a/src/c3nav/mesh/api.py
+++ b/src/c3nav/mesh/api.py
@@ -105,7 +105,7 @@ def firmware_by_id(request, firmware_id: int):
 def firmware_build_image(request, firmware_id: int, variant: str):
     try:
         build = FirmwareBuild.objects.get(version_id=firmware_id, variant=variant)
-        return build.firmware_image.model_dump()
+        return build.firmware_image.model_dump(mode="json")
     except FirmwareVersion.DoesNotExist:
         raise API404("Firmware or firmware build not found")
 
diff --git a/src/c3nav/mesh/consumers.py b/src/c3nav/mesh/consumers.py
index 7c6c0785..172a4cf9 100644
--- a/src/c3nav/mesh/consumers.py
+++ b/src/c3nav/mesh/consumers.py
@@ -364,7 +364,7 @@ class MeshConsumer(AsyncWebsocketConsumer):
     """
 
     async def log_received_message(self, src_node: MeshNode, msg: messages.MeshMessage):
-        as_json = msg.model_dump()
+        as_json = msg.model_dump(mode="json")
         await self.channel_layer.group_send("mesh_msg_received", {
             "type": "mesh.msg_received",
             "timestamp": timezone.now().strftime("%d.%m.%y %H:%M:%S.%f"),
diff --git a/src/c3nav/mesh/messages.py b/src/c3nav/mesh/messages.py
index a54f8cdd..36fd9d9b 100644
--- a/src/c3nav/mesh/messages.py
+++ b/src/c3nav/mesh/messages.py
@@ -350,7 +350,7 @@ class MeshMessage(BaseModel):
             "type": "mesh.send",
             "sender": sender,
             "exclude_uplink_address": exclude_uplink_address,
-            "msg": self.model_dump(),
+            "msg": self.model_dump(mode="json"),
         }
 
         if self.dst in (MESH_CHILDREN_ADDRESS, MESH_BROADCAST_ADDRESS):
diff --git a/src/c3nav/routing/api/positioning.py b/src/c3nav/routing/api/positioning.py
index bb0ad6d8..1179de9c 100644
--- a/src/c3nav/routing/api/positioning.py
+++ b/src/c3nav/routing/api/positioning.py
@@ -82,7 +82,7 @@ def locate_test(request):
         None
     )
     return {
-        "ranges": msg.parsed.model_dump()["ranges"],
+        "ranges": msg.parsed.model_dump(mode="json")["ranges"],
         "datetime": msg.datetime,
         "location": location.serialize(simple_geometry=True) if location else None
     }