diff --git a/library/psa_crypto_slot_management.c b/library/psa_crypto_slot_management.c
index b184ed08c9..fbcb26ebc8 100644
--- a/library/psa_crypto_slot_management.c
+++ b/library/psa_crypto_slot_management.c
@@ -440,6 +440,9 @@ psa_status_t psa_get_and_lock_key_slot(mbedtls_svc_key_id_t key,
     status = PSA_ERROR_INVALID_HANDLE;
 #endif /* MBEDTLS_PSA_CRYPTO_STORAGE_C || MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
 
+    if (status != PSA_SUCCESS) {
+        *p_slot = NULL;
+    }
 #if defined(MBEDTLS_THREADING_C)
     PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
                               &mbedtls_threading_key_slot_mutex));