diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index 48de3d0..56967cd 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -38,6 +38,9 @@
 #define MBEDTLS_SSL_TLS1_3_LABEL( name, string )       \
     .name = string,
 
+#define MBEDTLS_EVOLVE_INPUT_SIZE (PSA_HASH_MAX_SIZE > PSA_RAW_KEY_AGREEMENT_OUTPUT_MAX_SIZE)? \
+                                      PSA_HASH_MAX_SIZE : PSA_RAW_KEY_AGREEMENT_OUTPUT_MAX_SIZE
+
 struct mbedtls_ssl_tls13_labels_struct const mbedtls_ssl_tls13_labels =
 {
     /* This seems to work in C, despite the string literal being one
@@ -333,7 +336,7 @@
     psa_status_t abort_status = PSA_ERROR_CORRUPTION_DETECTED;
     size_t hlen, ilen;
     unsigned char tmp_secret[ PSA_MAC_MAX_SIZE ] = { 0 };
-    unsigned char tmp_input [ MBEDTLS_ECP_MAX_BYTES ] = { 0 };
+    unsigned char tmp_input [ MBEDTLS_EVOLVE_INPUT_SIZE ] = { 0 };
     psa_key_derivation_operation_t operation =
         PSA_KEY_DERIVATION_OPERATION_INIT;