diff --git a/tools/tsan_suppressions.txt b/tools/tsan_suppressions.txt
index 09e68cd2335ae760fae8839f03989b0aa9f4d2f0..765fa098f92c5e4b9d9438859e4a1188c43167f1 100644
--- a/tools/tsan_suppressions.txt
+++ b/tools/tsan_suppressions.txt
@@ -6,3 +6,6 @@ race:cleanse_ctr
 race:ssleay_rand_add
 race:ssleay_rand_bytes
 race:__sleep_for
+# protobuf has an idempotent write race in ByteSize
+# https://github.com/google/protobuf/issues/2169
+race:ByteSize