diff --git a/ChangeLog.d/fix-pms-ecdh-psa-client-size.txt b/ChangeLog.d/fix-pms-ecdh-psa-client-size.txt
new file mode 100644
index 0000000000..b90b278ebd
--- /dev/null
+++ b/ChangeLog.d/fix-pms-ecdh-psa-client-size.txt
@@ -0,0 +1,7 @@
+Bugfix
+   * Fix TLS 1.2 ECDHE handshakes failing in PSA-client-only
+     (MBEDTLS_PSA_CRYPTO_C disabled) builds when PSK
+     and ECJPAKE key-exchanges were disabled.
+     In this scenario ECDHE key agreement failed returning
+     PSA_ERROR_BUFFER_TOO_SMALL.
+     Fixes #10757.
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 00e28442d6..1761723715 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -653,13 +653,13 @@ union mbedtls_ssl_premaster_secret {
     unsigned char dummy; /* Make the union non-empty even with SSL disabled */
 #if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED)    || \
     defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED)
-    unsigned char _pms_ecdh[MBEDTLS_ECP_MAX_BYTES];    /* RFC 4492 5.10 */
+    unsigned char _pms_ecdh[PSA_RAW_KEY_AGREEMENT_OUTPUT_MAX_SIZE];    /* RFC 4492 5.10 */
 #endif
 #if defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
     unsigned char _pms_psk[4 + 2 * MBEDTLS_PSK_MAX_LEN];       /* RFC 4279 2 */
 #endif
 #if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED)
-    unsigned char _pms_ecdhe_psk[4 + MBEDTLS_ECP_MAX_BYTES
+    unsigned char _pms_ecdhe_psk[4 + PSA_RAW_KEY_AGREEMENT_OUTPUT_MAX_SIZE
                                  + MBEDTLS_PSK_MAX_LEN];       /* RFC 5489 2 */
 #endif
 #if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)