diff --git a/app/javascript/components/editor/ClientSideTestRunner/kernel/Kernel.ts b/app/javascript/components/editor/ClientSideTestRunner/kernel/Kernel.ts
index 223dc5360f..c2b8fb339f 100644
--- a/app/javascript/components/editor/ClientSideTestRunner/kernel/Kernel.ts
+++ b/app/javascript/components/editor/ClientSideTestRunner/kernel/Kernel.ts
@@ -104,8 +104,9 @@ export class Kernel {
       }
     })
 
-    const { env, preload, licence } = self.config
-    await self.#client.boot(entry.sysroot, toEnv(env), preload, licence)
+    const { env, licence } = self.config
+    const precompile = self.config.precompile ?? self.config.preload ?? []
+    await self.#client.boot(entry.sysroot, toEnv(env), precompile, licence)
 
     // The sysroot carries the language's tools but not the runner itself, so
     // /opt/test-runner is untarred on top of it. Part of boot rather than of a
diff --git a/app/javascript/components/editor/ClientSideTestRunner/kernel/kernelClient.ts b/app/javascript/components/editor/ClientSideTestRunner/kernel/kernelClient.ts
index bac1e16236..c4cdae857d 100644
--- a/app/javascript/components/editor/ClientSideTestRunner/kernel/kernelClient.ts
+++ b/app/javascript/components/editor/ClientSideTestRunner/kernel/kernelClient.ts
@@ -39,7 +39,7 @@ export interface KernelClient {
   boot(
     sysroot: string,
     env: string[],
-    preload: string[],
+    precompile: string[],
     licence?: Licence[]
   ): Request<void>
   untar(path: string, data: ArrayBuffer): Request<void>
@@ -62,6 +62,8 @@ export type KernelClientConstructor = new (options: {
 /** The kernel's boot.json, served beside sysroot.tar. */
 export type BootConfig = {
   env: Record<string, string>
-  preload: string[]
+  precompile?: string[]
+  // The old name for precompile. Remove once every boot.json uses precompile.
+  preload?: string[]
   licence?: Licence[]
 }