diff --git a/docs/architecture/psa-thread-safety.md b/docs/architecture/psa-thread-safety.md
index 1c80e3d34..fb2b96303 100644
--- a/docs/architecture/psa-thread-safety.md
+++ b/docs/architecture/psa-thread-safety.md
@@ -81,7 +81,7 @@ When `psa_destroy_key` is called on a key that is in use, guarantee 2. might be
 
 ### Key destruction long-term requirements
 
-The [PSA Crypto API specification](https://armmbed.github.io/mbed-crypto/html/api/keys/management.html#key-destruction) mandates that implementations make a best effort to ensure that that the key material cannot be recovered. In the long term, it would be good to guarantee that `psa_destroy_key` wipes all copies of the key material.
+The [PSA Crypto API specification](https://armmbed.github.io/mbed-crypto/html/api/keys/management.html#key-destruction) mandates that implementations make a best effort to ensure that the key material cannot be recovered. In the long term, it would be good to guarantee that `psa_destroy_key` wipes all copies of the key material.
 
 #### Summary of guarantees in the long term