diff --git a/crates/applications/wavefront/src/main.rs b/crates/applications/wavefront/src/main.rs
index 60f9a1c..c4dda65 100644
--- a/crates/applications/wavefront/src/main.rs
+++ b/crates/applications/wavefront/src/main.rs
@@ -11,7 +11,7 @@ use coremem::{mat, Driver};
 use coremem::geom::{Coord as _, Cube, Index};
 use coremem::units::Seconds;
 use coremem::sim::spirv::{self, SpirvSim};
-use coremem::stim::{Stimulus, TimeVarying as _, UniformStimulus};
+use coremem::stim::{RegionGated, TimeVarying as _, UniformStimulus};
 use coremem::cross::vec::Vec3;
 
 type Mat = mat::FullyGenericMaterial<f32>;
@@ -46,7 +46,7 @@ fn main() {
         Index::new(201, height*3/4, 1).to_meters(feature_size),
     );
     // emit a constant E/H delta over this region for 100 femtoseconds
-    let stim = Stimulus::new(
+    let stim = RegionGated::new(
         center_region,
         UniformStimulus::new(
             Vec3::new(2e19, 0.0, 0.0),  // E field (per second)
diff --git a/crates/coremem/src/stim.rs b/crates/coremem/src/stim.rs
index b95f799..9a5403e 100644
--- a/crates/coremem/src/stim.rs
+++ b/crates/coremem/src/stim.rs
@@ -224,23 +224,23 @@ impl AbstractStimulus for RngStimulus {
 
 /// Apply a time-varying stimulus uniformly across some region
 #[derive(Clone)]
-pub struct Stimulus<R, T> {
+pub struct RegionGated<R, S> {
     region: R,
-    stim: T,
+    stim: S,
 }
 
-impl<R, T> Stimulus<R, T> {
-    pub fn new(region: R, stim: T) -> Self {
+impl<R, S> RegionGated<R, S> {
+    pub fn new(region: R, stim: S) -> Self {
         Self {
             region, stim
         }
     }
 }
 
-impl<R: Region + Sync, T: TimeVarying3 + Sync> AbstractStimulus for Stimulus<R, T> {
+impl<R: Region + Sync, S: AbstractStimulus + Sync> AbstractStimulus for RegionGated<R, S> {
     fn at(&self, t_sec: f32, pos: Meters) -> Fields {
         if self.region.contains(pos) {
-            self.stim.at(t_sec)
+            self.stim.at(t_sec, pos)
         } else {
             Fields::default()
         }