$ git diff build-support/bin/native/bootstrap.sh | cat
diff --git a/build-support/bin/native/bootstrap.sh b/build-support/bin/native/bootstrap.sh
index cdbf4bc..c3c395f 100644
--- a/build-support/bin/native/bootstrap.sh
+++ b/build-support/bin/native/bootstrap.sh
@@ -59,9 +59,9 @@ function ensure_build_prerequisites() {
         "<https://www.rustup.rs> ..."
     local readonly rustup=$(mktemp -t pants.rustup.XXXXXX)
     curl <https://sh.rustup.rs> -sSf > ${rustup}
-    sh ${rustup} -y --no-modify-path 1>&2
+    sh ${rustup} -y --no-modify-path --default-toolchain nightly 1>&2
     rm -f ${rustup}
-    ${RUSTUP_HOME}/bin/rustup override set stable 1>&2
+    ${RUSTUP_HOME}/bin/rustup override set nightly 1>&2
   fi
 
   if [[ -n "${target}" ]]