diff --git a/run-test.sh b/run-test.sh
index 798d60b..dda149c 100755
--- a/run-test.sh
+++ b/run-test.sh
@@ -39,6 +39,10 @@ cp "$MIRI_LIB_SRC/Cargo.lock" Cargo.lock
 # is just a re-export of the sysroot crate, so we don't get duplicate lang items.
 export MIRI_REPLACE_LIBRS_IF_NOT_TEST=1
 
+# Set the right rustflags.
+export RUSTFLAGS="${RUSTFLAGS:-} -Zforce-unstable-if-unmarked"
+export RUSTDOCFLAGS="${RUSTDOCFLAGS:-} -Zforce-unstable-if-unmarked"
+
 # run test
 export CARGO_TARGET_DIR=$(pwd)/target
 cargo miri test --manifest-path "library/$CRATE/Cargo.toml" "$@"
diff --git a/rust-version b/rust-version
index 67380bd..f52ef73 100644
--- a/rust-version
+++ b/rust-version
@@ -1 +1 @@
-nightly-2024-12-01
+nightly-2024-12-04