diff --git a/include/psa/crypto_extra.h b/include/psa/crypto_extra.h
index a10bb8b..9d26a7f 100644
--- a/include/psa/crypto_extra.h
+++ b/include/psa/crypto_extra.h
@@ -40,8 +40,8 @@
 #define PSA_CRYPTO_ITS_RANDOM_SEED_UID 0xFFFFFF52
 
 /* See config.h for definition */
-#if !defined(PSA_KEY_SLOT_COUNT)
-#define PSA_KEY_SLOT_COUNT 32
+#if !defined(MBEDTLS_PSA_KEY_SLOT_COUNT)
+#define MBEDTLS_PSA_KEY_SLOT_COUNT 32
 #endif
 
 /** \addtogroup attributes