diff --git a/.kokoro/build.sh b/.kokoro/build.sh
index 084b07b25..73c3b601f 100755
--- a/.kokoro/build.sh
+++ b/.kokoro/build.sh
@@ -93,6 +93,7 @@ samples)
         pushd ${SAMPLES_DIR}
         mvn -B \
           -ntp \
+          -Dprotobuf.version=4.29.4 \
           -DtrimStackTrace=false \
           -Dclirr.skip=true \
           -Denforcer.skip=true \