diff --git a/run-test.sh b/run-test.sh
index dda149c..84707ef 100755
--- a/run-test.sh
+++ b/run-test.sh
@@ -39,9 +39,13 @@ 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"
+# Set the right rustflags (this matches the rustc-build-sysroot defaults):
+# - `-Zforce-unstable-if-unmarked`` is always needed for sysroot builds
+# - `-Aunexpected_cfgs` since we do not want to be in the business of debugging unexpected_cfgs for
+#   the sysroot
+EXTRAFLAGS="-Zforce-unstable-if-unmarked -Aunexpected_cfgs"
+export RUSTFLAGS="${RUSTFLAGS:-} $EXTRAFLAGS"
+export RUSTDOCFLAGS="${RUSTDOCFLAGS:-} $EXTRAFLAGS"
 
 # run test
 export CARGO_TARGET_DIR=$(pwd)/target
diff --git a/rust-src.diff b/rust-src.diff
index e69de29..6ebfe67 100644
--- a/rust-src.diff
+++ b/rust-src.diff
@@ -0,0 +1,21 @@
+diff --git a/library/core/src/iter/sources/generator.rs b/library/core/src/iter/sources/generator.rs
+index c94232e09eb..155fa9368ad 100644
+--- a/library/core/src/iter/sources/generator.rs
++++ b/library/core/src/iter/sources/generator.rs
+@@ -9,8 +9,6 @@
+ ///
+ /// ```
+ /// #![feature(iter_macro, coroutines)]
+-/// # #[cfg(not(bootstrap))]
+-/// # {
+ ///
+ /// let it = std::iter::iter!{|| {
+ ///     yield 1;
+@@ -19,7 +17,6 @@
+ /// } }();
+ /// let v: Vec<_> = it.collect();
+ /// assert_eq!(v, [1, 2, 3]);
+-/// # }
+ /// ```
+ #[unstable(feature = "iter_macro", issue = "none", reason = "generators are unstable")]
+ #[allow_internal_unstable(coroutines, iter_from_coroutine)]
diff --git a/rust-version b/rust-version
index da3775b..e1c4235 100644
--- a/rust-version
+++ b/rust-version
@@ -1 +1 @@
-nightly-2025-06-01
+nightly-2025-06-06