diff --git a/.github/workflows/extension_tests.yml b/.github/workflows/extension_tests.yml
index 90c7552ee1cc16f2e2193cf7de2696202afacffd..d1aa004015383cc0b0ce8d461a196bc2ec86b233 100644
--- a/.github/workflows/extension_tests.yml
+++ b/.github/workflows/extension_tests.yml
@@ -6,6 +6,7 @@ env:
   RUST_BACKTRACE: '1'
   CARGO_INCREMENTAL: '0'
   ZED_EXTENSION_CLI_SHA: 7cfce605704d41ca247e3f84804bf323f6c6caaf
+  RUSTUP_TOOLCHAIN: stable
   CARGO_BUILD_TARGET: wasm32-wasip2
 on:
   workflow_call: {}
diff --git a/tooling/xtask/src/tasks/workflows/extension_tests.rs b/tooling/xtask/src/tasks/workflows/extension_tests.rs
index 9d7e233d562fd634960454a6490d8a861459763d..c3de2e111acdd3b44753fbb44f1a71ee416aa58f 100644
--- a/tooling/xtask/src/tasks/workflows/extension_tests.rs
+++ b/tooling/xtask/src/tasks/workflows/extension_tests.rs
@@ -32,6 +32,7 @@ pub(crate) fn extension_tests() -> Workflow {
         .add_env(("RUST_BACKTRACE", 1))
         .add_env(("CARGO_INCREMENTAL", 0))
         .add_env(("ZED_EXTENSION_CLI_SHA", ZED_EXTENSION_CLI_SHA))
+        .add_env(("RUSTUP_TOOLCHAIN", "stable"))
         .add_env((
             "CARGO_BUILD_TARGET",
             extension::extension_builder::RUST_TARGET,