diff --git a/examples/cpp/csm/csm_greeter_client.cc b/examples/cpp/csm/csm_greeter_client.cc
index f780928c683..6ad635f5a63 100644
--- a/examples/cpp/csm/csm_greeter_client.cc
+++ b/examples/cpp/csm/csm_greeter_client.cc
@@ -24,6 +24,7 @@
 
 #include "absl/flags/flag.h"
 #include "absl/flags/parse.h"
+#include "absl/strings/str_join.h"
 #include "absl/strings/str_split.h"
 #include "opentelemetry/exporters/prometheus/exporter_factory.h"
 #include "opentelemetry/exporters/prometheus/exporter_options.h"