diff --git a/include/mbedtls/rsa.h b/include/mbedtls/rsa.h
index 35185df..54653df 100644
--- a/include/mbedtls/rsa.h
+++ b/include/mbedtls/rsa.h
@@ -206,7 +206,7 @@
  * \return         0 if successful, or an MBEDTLS_ERR_RSA_XXX error code
  *
  * \note           This function does NOT take care of message
- *                 padding. Also, be sure to set input[0] = 0 or assure that
+ *                 padding. Also, be sure to set input[0] = 0 or ensure that
  *                 input is smaller than N.
  *
  * \note           The input and output buffers must be large