diff --git a/aes.c b/aes.c
index 151355a..7dd06e4 100644
--- a/aes.c
+++ b/aes.c
@@ -1,6 +1,6 @@
 /*
 
-This is the implementation of the AES128 algorithm, specifically ECB mode.
+This is an implementation of the AES128 algorithm, specifically ECB mode.
 
 The implementation is verified against the test vectors in:
   National Institute of Standards and Technology Special Publication 800-38A 2001 ED