diff --git a/common/BUILD b/common/BUILD
index ff36da33f..1fb67395a 100644
--- a/common/BUILD
+++ b/common/BUILD
@@ -428,6 +428,7 @@ cc_library(
     name = "source",
     srcs = ["source.cc"],
     hdrs = ["source.h"],
+    copts = ["-Wno-character-conversion"],
     deps = [
         "//internal:unicode",
         "//internal:utf8",