diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 251d4f0..0b755e3 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -3671,6 +3671,17 @@
  */
 //#define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA256
 
+/** \def PSA_KEY_SLOT_COUNT
+ * Restrict the PSA library to supporting a maximum amount of simultaneously
+ * loaded keys. A loaded key is a key stored by the PSA Crypto core as a
+ * volatile key, or a persistent key which is loaded temporarily by the
+ * library as part of a crypto operation in flight.
+ *
+ * If this option is unset, the library will fall back to a default value of
+ * 32 keys.
+ */
+//#define PSA_KEY_SLOT_COUNT 32
+
 /* SSL Cache options */
 //#define MBEDTLS_SSL_CACHE_DEFAULT_TIMEOUT       86400 /**< 1 day  */
 //#define MBEDTLS_SSL_CACHE_DEFAULT_MAX_ENTRIES      50 /**< Maximum entries in cache */