diff --git a/src/core/tsi/alts/crypt/aes_gcm.cc b/src/core/tsi/alts/crypt/aes_gcm.cc
index c638ce7..3dc3b2e 100644
--- a/src/core/tsi/alts/crypt/aes_gcm.cc
+++ b/src/core/tsi/alts/crypt/aes_gcm.cc
@@ -28,6 +28,7 @@
 #include <openssl/evp.h>
 #include <openssl/hmac.h>
 #include <string.h>
+#include <cstdio>
 
 #include <grpc/support/alloc.h>