diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 696e830..8c2c543 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -706,15 +706,9 @@
                                          size_t buffer_length)
 {
 #if defined(MBEDTLS_PSA_STATIC_KEY_SLOTS)
-    if (slot->key.in_use) {
-        return PSA_ERROR_ALREADY_EXISTS;
-    }
-
     if (buffer_length > ((size_t) MBEDTLS_PSA_STATIC_KEY_SLOT_BUFFER_SIZE)) {
         return PSA_ERROR_NOT_SUPPORTED;
     }
-
-    slot->key.in_use = 1;
 #else
     if (slot->key.data != NULL) {
         return PSA_ERROR_ALREADY_EXISTS;
@@ -1189,9 +1183,7 @@
 
 psa_status_t psa_remove_key_data_from_memory(psa_key_slot_t *slot)
 {
-#if defined(MBEDTLS_PSA_STATIC_KEY_SLOTS)
-    slot->key.in_use = 0;
-#else /* MBEDTLS_PSA_STATIC_KEY_SLOTS */
+#if !defined(MBEDTLS_PSA_STATIC_KEY_SLOTS)
     if (slot->key.data != NULL) {
         mbedtls_zeroize_and_free(slot->key.data, slot->key.bytes);
     }
@@ -2113,13 +2105,7 @@
      * storage ( thus not in the case of importing a key in a secure element
      * with storage ( MBEDTLS_PSA_CRYPTO_SE_C ) ),we have to allocate a
      * buffer to hold the imported key material. */
-#if defined(MBEDTLS_PSA_STATIC_KEY_SLOTS)
-    int is_slot_unused = (slot->key.in_use == 0);
-#else
-    int is_slot_unused = (slot->key.data == NULL);
-#endif
-
-    if (is_slot_unused) {
+    if (slot->key.bytes == 0) {
         if (psa_key_lifetime_is_external(attributes->lifetime)) {
             status = psa_driver_wrapper_get_key_buffer_size_from_key_data(
                 attributes, data, data_length, &storage_size);
@@ -8036,13 +8022,7 @@
      * storage ( thus not in the case of generating a key in a secure element
      * with storage ( MBEDTLS_PSA_CRYPTO_SE_C ) ),we have to allocate a
      * buffer to hold the generated key material. */
-#if defined(MBEDTLS_PSA_STATIC_KEY_SLOTS)
-    int is_slot_unused = (slot->key.in_use == 0);
-#else
-    int is_slot_unused = (slot->key.data == NULL);
-#endif
-
-    if (is_slot_unused) {
+    if (slot->key.bytes == 0) {
         if (PSA_KEY_LIFETIME_GET_LOCATION(attributes->lifetime) ==
             PSA_KEY_LOCATION_LOCAL_STORAGE) {
             status = psa_validate_key_type_and_size_for_key_generation(