diff --git a/src/aare/daq/operations/rotation/service.py b/src/aare/daq/operations/rotation/service.py
index da7c5258..1246c6dd 100644
--- a/src/aare/daq/operations/rotation/service.py
+++ b/src/aare/daq/operations/rotation/service.py
@@ -39,9 +39,11 @@ class RotationService:
             self.ctx.deps.devs.set_dtz(request.dtz, wait=True)
 
         if request.screening:
+            if request.wedge_omega_deg is None:
+                raise ValueError("Must supply a wedge angle for screening requests")
             self.logger.debug(f"Starting screening scan with {request.steps} steps")
             self.ctx.deps.devs.aerotech.screening_scan(
-                rotation_deg=request.steps * request.incr_omega_deg,
+                rotation_deg=request.incr_omega_deg,
                 wedge_deg=request.wedge_omega_deg,
                 time_sec=total_time,
                 steps=request.steps,