README.md: fix typo
diff --git a/README.md b/README.md
index b9f44e0..faf6066 100644
--- a/README.md
+++ b/README.md
@@ -125,6 +125,6 @@
It was considered to add an additional layer of end2end encryption for the
pseudonymized IMSIs on top, but this is out-of-scope for this project. For
-reference, once could pre-provision a random "imsi_pseudo_key" with the SIM
+reference, one could pre-provision a random "imsi_pseudo_key" with the SIM
card, store it in the pseudo IMSI table in the HLR, and deploy a new encryption
key together with each new pseudo IMSI, attached to the SMS.