diff --git a/src/BearSSLClient.h b/src/BearSSLClient.h
index 700bb9a..1d54e5c 100644
--- a/src/BearSSLClient.h
+++ b/src/BearSSLClient.h
@@ -25,6 +25,18 @@
 #ifndef _BEAR_SSL_CLIENT_H_
 #define _BEAR_SSL_CLIENT_H_
 
+#if defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_OPTA) || defined(ARDUINO_GIGA)
+
+#ifndef BEAR_SSL_CLIENT_OBUF_SIZE
+#define BEAR_SSL_CLIENT_OBUF_SIZE 2048
+#endif
+
+#ifndef BEAR_SSL_CLIENT_IBUF_SIZE
+#define BEAR_SSL_CLIENT_IBUF_SIZE 32768
+#endif
+
+#else
+
 #ifndef BEAR_SSL_CLIENT_OBUF_SIZE
 #define BEAR_SSL_CLIENT_OBUF_SIZE 512 + 85
 #endif
@@ -33,6 +45,8 @@
 #define BEAR_SSL_CLIENT_IBUF_SIZE 8192 + 85 + 325 - BEAR_SSL_CLIENT_OBUF_SIZE
 #endif
 
+#endif
+
 #ifndef BEAR_SSL_CLIENT_CHAIN_SIZE
 #define BEAR_SSL_CLIENT_CHAIN_SIZE 3
 #endif