diff --git a/ci/build.sh b/ci/build.sh
index 2588166e8495b..3a3a00d81caf7 100644
--- a/ci/build.sh
+++ b/ci/build.sh
@@ -10,13 +10,19 @@ set -ex
 : "${TOOLCHAIN?The TOOLCHAIN environment variable must be set.}"
 : "${OS?The OS environment variable must be set.}"
 
-RUST=${TOOLCHAIN}
+case "$TARGET" in
+    # FIXME: Unpin once mips' components are available on nightly.
+    # https://rust-lang.github.io/rustup-components-history/mips-unknown-linux-gnu.html
+    *mips*) RUST=nightly-2023-07-04;;
+    *) RUST=${TOOLCHAIN};;
+esac
 
 echo "Testing Rust ${RUST} on ${OS}"
 
-if [ "${TOOLCHAIN}" = "nightly" ] ; then
-    rustup component add rust-src
-fi
+case "$RUST" in
+    *nightly*) rustup component add rust-src;;
+    *) ;;
+esac
 
 test_target() {
     BUILD_CMD="${1}"
diff --git a/ci/install-rust.sh b/ci/install-rust.sh
index 5b50c624cbd66..3ce81e6299932 100644
--- a/ci/install-rust.sh
+++ b/ci/install-rust.sh
@@ -12,6 +12,9 @@ else
   # https://github.com/rust-lang/rust/issues/103673 contains related information.
   case "$TARGET" in
     *android*) toolchain=nightly-2022-10-09;;
+    # FIXME: Unpin once mips' components are available on nightly.
+    # https://rust-lang.github.io/rustup-components-history/mips-unknown-linux-gnu.html
+    *mips*) toolchain=nightly-2023-07-04;;
     *) toolchain=nightly;;
   esac
 fi