diff --git a/src/ess/beer/io.py b/src/ess/beer/io.py
index 20bb2e3d..53e3f0b8 100644
--- a/src/ess/beer/io.py
+++ b/src/ess/beer/io.py
@@ -10,7 +10,7 @@
     Filename,
     ModulationPeriod,
     SampleRun,
-    TwoThetaMaskFunction,
+    TwoThetaLimits,
     WavelengthDefinitionChopperDelay,
 )
 
@@ -122,19 +122,27 @@ def load_beer_mcstas(f: str | Path | h5py.File) -> sc.DataGroup:
     )
 
 
+def _not_between(x, a, b):
+    return (x < a) | (b < x)
+
+
 def load_beer_mcstas_provider(
-    fname: Filename[SampleRun], two_theta_mask: TwoThetaMaskFunction
+    fname: Filename[SampleRun], two_theta_limits: TwoThetaLimits
 ) -> DetectorData[SampleRun]:
     da = load_beer_mcstas(fname)
     da = (
         sc.DataGroup(
             {
-                k: v.assign_masks(two_theta=two_theta_mask(v.coords['two_theta']))
+                k: v.assign_masks(
+                    two_theta=_not_between(v.coords['two_theta'], *two_theta_limits)
+                )
                 for k, v in da.items()
             }
         )
         if isinstance(da, sc.DataGroup)
-        else da.assign_masks(two_theta=two_theta_mask(da.coords['two_theta']))
+        else da.assign_masks(
+            two_theta=_not_between(da.coords['two_theta'], *two_theta_limits)
+        )
     )
     return DetectorData[SampleRun](da)
 
diff --git a/src/ess/beer/types.py b/src/ess/beer/types.py
index 592cc00e..e729e10a 100644
--- a/src/ess/beer/types.py
+++ b/src/ess/beer/types.py
@@ -1,4 +1,3 @@
-from collections.abc import Callable
 from typing import NewType
 
 import sciline
@@ -18,9 +17,7 @@ class StreakClusteredData(sciline.Scope[RunType, sc.DataArray], sc.DataArray):
 DetectorTofData = DetectorTofData
 
 
-TwoThetaMaskFunction = NewType(
-    'TwoThetaMaskFunction', Callable[[sc.Variable], sc.Variable]
-)
+TwoThetaLimits = NewType('TwoThetaLimits', tuple[sc.Variable, sc.Variable])
 
 TofCoordTransformGraph = NewType("TofCoordTransformGraph", dict)
 
diff --git a/src/ess/beer/workflow.py b/src/ess/beer/workflow.py
index e9428cf8..f47fdcb0 100644
--- a/src/ess/beer/workflow.py
+++ b/src/ess/beer/workflow.py
@@ -11,14 +11,14 @@
     PulseLength,
     RunType,
     SampleRun,
-    TwoThetaMaskFunction,
+    TwoThetaLimits,
 )
 
 default_parameters = {
     PulseLength: sc.scalar(0.003, unit='s'),
-    TwoThetaMaskFunction: lambda two_theta: (
-        (two_theta >= sc.scalar(105, unit='deg').to(unit='rad', dtype='float64'))
-        | (two_theta <= sc.scalar(75, unit='deg').to(unit='rad', dtype='float64'))
+    TwoThetaLimits: (
+        sc.scalar(75, unit='deg').to(unit='rad', dtype='float64'),
+        sc.scalar(105, unit='deg').to(unit='rad', dtype='float64'),
     ),
 }