diff --git a/src/simulator/api-wasm/src/lib.rs b/src/simulator/api-wasm/src/lib.rs
index 7fc1be24..68789e2f 100644
--- a/src/simulator/api-wasm/src/lib.rs
+++ b/src/simulator/api-wasm/src/lib.rs
@@ -228,8 +228,8 @@ impl WasmClimatePhysics {
 
     /// Run one turn of climate simulation.
     #[wasm_bindgen(js_name = "processStep")]
-    pub fn process_step(&mut self, grid: &mut WasmGrid, turn: u32, seed: u32) {
-        self.inner.process_step(&mut grid.inner, turn, seed as u64);
+    pub fn process_step(&mut self, grid: &mut WasmGrid, turn: u32, seed: u32, dt: f32) {
+        self.inner.process_step(&mut grid.inner, turn, seed as u64, dt);
     }
 
     /// Run atmospheric chemistry using the spec stored at construction time.
@@ -265,8 +265,8 @@ impl WasmEcologyPhysics {
 
     /// Run one tick of ecology simulation.
     #[wasm_bindgen(js_name = "processStep")]
-    pub fn process_step(&mut self, grid: &mut WasmGrid) {
-        self.inner.process_step(&mut grid.inner);
+    pub fn process_step(&mut self, grid: &mut WasmGrid, dt: f32) {
+        self.inner.process_step(&mut grid.inner, dt);
     }
 }