diff --git a/src/redirect.rs b/src/redirect.rs
index ec487f8..07c9461 100644
--- a/src/redirect.rs
+++ b/src/redirect.rs
@@ -1,5 +1,6 @@
-use std::collections::{HashMap, HashSet};
+use std::collections::HashSet;
 
+use indexmap::IndexMap;
 use naga::{Block, Expression, Function, Handle, Module, Statement};
 use thiserror::Error;
 
@@ -183,8 +184,9 @@ impl Redirector {
     }
 
     pub fn into_module(self) -> Result<naga::Module, RedirectError> {
-        // reorder functions so that dependents come first
-        let mut requirements: HashMap<_, _> = self
+        // reorder functions so that dependents come first. IndexMap (not HashMap)
+        // so the emission order is deterministic across runs.
+        let mut requirements: IndexMap<_, _> = self
             .module
             .functions
             .iter()