diff --git a/src/simulator/api-gdext/src/lib.rs b/src/simulator/api-gdext/src/lib.rs
index 63e20413..496b00d7 100644
--- a/src/simulator/api-gdext/src/lib.rs
+++ b/src/simulator/api-gdext/src/lib.rs
@@ -147,10 +147,10 @@ impl GdClimatePhysics {
 
     /// Run one turn of climate simulation on the given grid.
     #[func]
-    fn process_step(&mut self, mut grid: Gd<GdGridState>, turn: i64, seed: i64) {
+    fn process_step(&mut self, mut grid: Gd<GdGridState>, turn: i64, seed: i64, dt: f64) {
         match &mut self.inner {
             Some(physics) => {
-                physics.process_step(&mut grid.bind_mut().inner, turn as u32, seed as u64);
+                physics.process_step(&mut grid.bind_mut().inner, turn as u32, seed as u64, dt as f32);
             }
             None => {
                 godot_error!("GdClimatePhysics::process_step called before initialize()");
@@ -182,8 +182,8 @@ impl IRefCounted for GdEcologyPhysics {
 impl GdEcologyPhysics {
     /// Run one tick of ecology simulation (flora succession + fauna habitat).
     #[func]
-    fn process_step(&mut self, mut grid: Gd<GdGridState>) {
-        self.inner.process_step(&mut grid.bind_mut().inner);
+    fn process_step(&mut self, mut grid: Gd<GdGridState>, dt: f64) {
+        self.inner.process_step(&mut grid.bind_mut().inner, dt as f32);
     }
 }