diff --git a/robot-server/robot_server/runs/router/base_router.py b/robot-server/robot_server/runs/router/base_router.py
index eeaf8b9a7a8..3b0e7040e02 100644
--- a/robot-server/robot_server/runs/router/base_router.py
+++ b/robot-server/robot_server/runs/router/base_router.py
@@ -52,6 +52,7 @@
     ActiveNozzleLayout,
     RunCurrentState,
     CommandLinkNoMeta,
+    NozzleLayoutConfig,
 )
 from ..run_auto_deleter import RunAutoDeleter
 from ..run_models import Run, BadRun, RunCreate, RunUpdate
@@ -576,7 +577,7 @@ async def get_current_state(
             pipetteId: ActiveNozzleLayout.construct(
                 startingNozzle=nozzle_map.starting_nozzle,
                 activeNozzles=list(nozzle_map.map_store.keys()),
-                config=nozzle_map.configuration.value,
+                config=NozzleLayoutConfig(nozzle_map.configuration.value.lower()),
             )
             for pipetteId, nozzle_map in active_nozzle_maps.items()
         }
diff --git a/robot-server/robot_server/runs/run_models.py b/robot-server/robot_server/runs/run_models.py
index f2573306fa7..962c3ab51e7 100644
--- a/robot-server/robot_server/runs/run_models.py
+++ b/robot-server/robot_server/runs/run_models.py
@@ -1,5 +1,7 @@
 """Request and response models for run resources."""
 from datetime import datetime
+
+from enum import Enum
 from pydantic import BaseModel, Field
 from typing import List, Optional, Literal, Dict
 
@@ -280,6 +282,16 @@ class LabwareDefinitionSummary(BaseModel):
     )
 
 
+class NozzleLayoutConfig(str, Enum):
+    """Possible valid nozzle configurations."""
+
+    COLUMN = "column"
+    ROW = "row"
+    SINGLE = "single"
+    FULL = "full"
+    SUBRECT = "subrect"
+
+
 class ActiveNozzleLayout(BaseModel):
     """Details about the active nozzle layout for a pipette used in the current run."""
 
@@ -290,7 +302,9 @@ class ActiveNozzleLayout(BaseModel):
         ...,
         description="A map of all the pipette nozzles active in the current configuration.",
     )
-    config: str = Field(..., description="The nozzle configuration type.")
+    config: NozzleLayoutConfig = Field(
+        ..., description="The active nozzle configuration."
+    )
 
 
 class RunCurrentState(BaseModel):
diff --git a/robot-server/tests/runs/router/test_base_router.py b/robot-server/tests/runs/router/test_base_router.py
index 8d244cd9d0e..37e5cd6dd3d 100644
--- a/robot-server/tests/runs/router/test_base_router.py
+++ b/robot-server/tests/runs/router/test_base_router.py
@@ -46,6 +46,7 @@
     RunCurrentState,
     ActiveNozzleLayout,
     CommandLinkNoMeta,
+    NozzleLayoutConfig,
 )
 from robot_server.runs.run_orchestrator_store import RunConflictError
 from robot_server.runs.run_data_manager import (
@@ -868,7 +869,9 @@ async def test_get_current_state_success(
     assert result.content.data == RunCurrentState.construct(
         activeNozzleLayouts={
             "mock-pipette-id": ActiveNozzleLayout(
-                startingNozzle="A1", activeNozzles=["A1"], config="FULL"
+                startingNozzle="A1",
+                activeNozzles=["A1"],
+                config=NozzleLayoutConfig.FULL,
             )
         }
     )