diff --git a/ChangeLog.d/fix-concurrently-loading-non-existent-keys.txt b/ChangeLog.d/fix-concurrently-loading-non-existent-keys.txt
new file mode 100644
index 0000000000..8a406a12e8
--- /dev/null
+++ b/ChangeLog.d/fix-concurrently-loading-non-existent-keys.txt
@@ -0,0 +1,4 @@
+Bugfix
+   * Fix rare concurrent access bug where attempting to operate on a
+     non-existent key while concurrently creating a new key could potentially
+     corrupt the key store.
diff --git a/library/psa_crypto_slot_management.c b/library/psa_crypto_slot_management.c
index b184ed08c9..9986a44969 100644
--- a/library/psa_crypto_slot_management.c
+++ b/library/psa_crypto_slot_management.c
@@ -424,6 +424,8 @@ psa_status_t psa_get_and_lock_key_slot(mbedtls_svc_key_id_t key,
     if (status != PSA_SUCCESS) {
         psa_wipe_key_slot(*p_slot);
 
+        /* If the key does not exist, we need to return
+         * PSA_ERROR_INVALID_HANDLE. */
         if (status == PSA_ERROR_DOES_NOT_EXIST) {
             status = PSA_ERROR_INVALID_HANDLE;
         }
@@ -440,6 +442,9 @@ 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));
diff --git a/library/psa_crypto_slot_management.h b/library/psa_crypto_slot_management.h
index bcfc9d8adc..a84be7d837 100644
--- a/library/psa_crypto_slot_management.h
+++ b/library/psa_crypto_slot_management.h
@@ -58,6 +58,9 @@ static inline int psa_key_id_is_volatile(psa_key_id_t key_id)
  * It is the responsibility of the caller to call psa_unregister_read(slot)
  * when they have finished reading the contents of the slot.
  *
+ * On failure, `*p_slot` is set to NULL. This ensures that it is always valid
+ * to call psa_unregister_read on the returned slot.
+ *
  * \param key           Key identifier to query.
  * \param[out] p_slot   On success, `*p_slot` contains a pointer to the
  *                      key slot containing the description of the key