diff --git a/src/core/tsi/alts/crypt/aes_gcm.cc b/src/core/tsi/alts/crypt/aes_gcm.cc
index b761224..88a3d6b 100644
--- a/src/core/tsi/alts/crypt/aes_gcm.cc
+++ b/src/core/tsi/alts/crypt/aes_gcm.cc
@@ -19,6 +19,7 @@
 #include <grpc/support/port_platform.h>
 
 #include <string.h>
+#include <cstdio>
 
 #include <openssl/bio.h>
 #include <openssl/buffer.h>
