diff --git a/blade-helpers/src/hud.rs b/blade-helpers/src/hud.rs
index efcba8c6..4d0579a0 100644
--- a/blade-helpers/src/hud.rs
+++ b/blade-helpers/src/hud.rs
@@ -33,6 +33,7 @@ impl ExposeHud for blade_render::RayConfig {
                 .text("T min")
                 .logarithmic(true),
         );
+        ui.checkbox(&mut self.pairwise_mis, "Pairwise MIS");
     }
 }
 
diff --git a/blade-render/code/ray-trace.wgsl b/blade-render/code/ray-trace.wgsl
index 7271c89f..9e0726e6 100644
--- a/blade-render/code/ray-trace.wgsl
+++ b/blade-render/code/ray-trace.wgsl
@@ -12,9 +12,6 @@
 
 const PI: f32 = 3.1415926;
 const MAX_RESAMPLE: u32 = 4u;
-// See "9.1 pairwise mis for robust reservoir reuse"
-// "Correlations and Reuse for Fast and Accurate Physically Based Light Transport"
-const PAIRWISE_MIS: bool = true;
 // See "DECOUPLING SHADING AND REUSE" in
 // "Rearchitecting Spatiotemporal Resampling for Production"
 const DECOUPLED_SHADING: bool = false;
@@ -36,9 +33,10 @@ struct MainParams {
     spatial_tap_confidence: f32,
     spatial_min_distance: i32,
     t_start: f32,
+    use_pairwise_mis: u32,
     use_motion_vectors: u32,
-    grid_scale: vec2<u32>,
     temporal_accumulation_weight: f32,
+    grid_scale: vec2<u32>,
 }
 
 var<uniform> camera: CameraParams;
@@ -414,7 +412,7 @@ fn resample(
     var src: LiveReservoir;
     let neighbor = other.reservoir;
     var rr = ResampleResult();
-    if (PAIRWISE_MIS) {
+    if (parameters.use_pairwise_mis != 0u) {
         let canonical = base.canonical;
         let neighbor_history = min(neighbor.confidence, max_confidence);
         {   // scoping this to hint the register allocation
@@ -485,14 +483,12 @@ fn finalize_resampling(
     base: ResampleBase, mis_canonical: f32, rng: ptr<function, RandomState>,
 ) -> ResampleOutput {
     var canonical = base.canonical;
-    var effective_history = canonical.history;
-    if (PAIRWISE_MIS)
-    {
+    if (parameters.use_pairwise_mis != 0u) {
         canonical.weight_sum *= mis_canonical / canonical.history;
-        effective_history = 1.0 + base.accepted_count;
     }
     merge_reservoir(reservoir, canonical, random_gen(rng));
 
+    let effective_history = select((*reservoir).history, 1.0 + base.accepted_count, parameters.use_pairwise_mis != 0u);
     var ro = ResampleOutput();
     ro.reservoir = pack_reservoir_detail(*reservoir, effective_history);
 
diff --git a/blade-render/src/render/mod.rs b/blade-render/src/render/mod.rs
index 9e692e17..4b18eecd 100644
--- a/blade-render/src/render/mod.rs
+++ b/blade-render/src/render/mod.rs
@@ -105,6 +105,9 @@ pub struct RayConfig {
     /// outside of the original workgroup pixel bounds.
     pub group_mixer: u32,
     pub t_start: f32,
+    /// See "9.1 pairwise mis for robust reservoir reuse"
+    /// "Correlations and Reuse for Fast and Accurate Physically Based Light Transport"
+    pub pairwise_mis: bool,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
@@ -370,10 +373,10 @@ struct MainParams {
     spatial_confidence: f32,
     spatial_min_distance: u32,
     t_start: f32,
+    use_pairwise_mis: u32,
     use_motion_vectors: u32,
-    grid_scale: [u32; 2],
     temporal_accumulation_weight: f32,
-    pad: f32,
+    grid_scale: [u32; 2],
 }
 
 #[derive(blade_macros::ShaderData)]
@@ -1094,14 +1097,14 @@ impl Renderer {
                         spatial_confidence: ray_config.spatial_confidence,
                         spatial_min_distance: ray_config.spatial_min_distance,
                         t_start: ray_config.t_start,
+                        use_pairwise_mis: ray_config.pairwise_mis as u32,
                         use_motion_vectors: (self.frame_scene_built == self.frame_index) as u32,
-                        grid_scale,
                         temporal_accumulation_weight: if denoiser_config.enabled {
                             denoiser_config.temporal_weight
                         } else {
                             1.0
                         },
-                        pad: 0.0,
+                        grid_scale,
                     },
                     acc_struct: self.acceleration_structure,
                     prev_acc_struct: if self.frame_scene_built < self.frame_index
diff --git a/examples/scene/main.rs b/examples/scene/main.rs
index 10320e18..a6be3e9d 100644
--- a/examples/scene/main.rs
+++ b/examples/scene/main.rs
@@ -258,7 +258,7 @@ impl Example {
             render_times: VecDeque::with_capacity(FRAME_TIME_HISTORY),
             ray_config: blade_render::RayConfig {
                 num_environment_samples: 1,
-                environment_importance_sampling: false,
+                environment_importance_sampling: true,
                 temporal_tap: true,
                 temporal_confidence: 10.0,
                 spatial_taps: 1,
@@ -266,6 +266,7 @@ impl Example {
                 spatial_min_distance: 4,
                 group_mixer: 10,
                 t_start: 0.1,
+                pairwise_mis: true,
             },
             denoiser_config: blade_render::DenoiserConfig {
                 enabled: true,
diff --git a/src/lib.rs b/src/lib.rs
index 7a2c7a54..a91c33b2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -483,7 +483,7 @@ impl Engine {
             },
             ray_config: blade_render::RayConfig {
                 num_environment_samples: 1,
-                environment_importance_sampling: false,
+                environment_importance_sampling: true,
                 temporal_tap: true,
                 temporal_confidence: 10.0,
                 spatial_taps: 1,
@@ -491,6 +491,7 @@ impl Engine {
                 spatial_min_distance: 4,
                 group_mixer: 10,
                 t_start: 0.01,
+                pairwise_mis: true,
             },
             denoiser_config: blade_render::DenoiserConfig {
                 enabled: true,