diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index 9ae51c9..4c676c5 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -3761,7 +3761,7 @@
  */
 //#define MBEDTLS_SSL_DTLS_MAX_BUFFERING             32768
 
-//#define MBEDTLS_PSK_MAX_LEN               32 /**< Max size of TLS pre-shared keys, in bytes (default 256 bits) */
+//#define MBEDTLS_PSK_MAX_LEN               32 /**< Max size of TLS pre-shared keys, in bytes (default 256 or 384 bits) */
 //#define MBEDTLS_SSL_COOKIE_TIMEOUT        60 /**< Default expiration delay of DTLS cookies, in seconds if HAVE_TIME, or in number of cookies issued */
 
 /**
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 4b954bb..0df142d 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -599,8 +599,22 @@
  * Size defines
  */
 #if !defined(MBEDTLS_PSK_MAX_LEN)
-#define MBEDTLS_PSK_MAX_LEN            32 /* 256 bits */
+/*
+ * If the library supports TLS 1.3 tickets and the cipher suite
+ * TLS1-3-AES-256-GCM-SHA384, set the PSK maximum length to 48 instead of 32.
+ * That way, the TLS 1.3 client and server are able to resume sessions where
+ * the cipher suite was TLS1-3-AES-256-GCM-SHA384 (pre-shared keys are 48
+ * bytes long is that case).
+ */
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3) && \
+    defined(MBEDTLS_SSL_SESSION_TICKETS) && \
+    defined(MBEDTLS_AES_C) && defined(MBEDTLS_GCM_C) && \
+    defined(MBEDTLS_HAS_ALG_SHA_384_VIA_MD_OR_PSA_BASED_ON_USE_PSA)
+#define MBEDTLS_PSK_MAX_LEN 48 /* 384 bits */
+#else
+#define MBEDTLS_PSK_MAX_LEN 32 /* 256 bits */
 #endif
+#endif /* !MBEDTLS_PSK_MAX_LEN */
 
 /* Dummy type used only for its size */
 union mbedtls_ssl_premaster_secret {