diff --git a/include/mbedtls/x509.h b/include/mbedtls/x509.h
index 9ae825c..63aae32 100644
--- a/include/mbedtls/x509.h
+++ b/include/mbedtls/x509.h
@@ -77,7 +77,7 @@
 #define MBEDTLS_ERR_X509_ALLOC_FAILED                     -0x2880  /**< Allocation of memory failed. */
 #define MBEDTLS_ERR_X509_FILE_IO_ERROR                    -0x2900  /**< Read/write of file failed. */
 #define MBEDTLS_ERR_X509_BUFFER_TOO_SMALL                 -0x2980  /**< Destination buffer is too small. */
-#define MBEDTLS_ERR_X509_FATAL_ERROR                      -0x3000  /**< A fatal error occured, eg the chain is too long or the vrfy callback failed. */
+#define MBEDTLS_ERR_X509_FATAL_ERROR                      -0x3000  /**< A fatal error occurred, eg the chain is too long or the vrfy callback failed. */
 /* \} name */
 
 /**
@@ -250,7 +250,7 @@
  *
  * \param to       mbedtls_x509_time to check
  *
- * \return         1 if the given time is in the past or an error occured,
+ * \return         1 if the given time is in the past or an error occurred,
  *                 0 otherwise.
  */
 int mbedtls_x509_time_is_past( const mbedtls_x509_time *to );
@@ -264,7 +264,7 @@
  *
  * \param from     mbedtls_x509_time to check
  *
- * \return         1 if the given time is in the future or an error occured,
+ * \return         1 if the given time is in the future or an error occurred,
  *                 0 otherwise.
  */
 int mbedtls_x509_time_is_future( const mbedtls_x509_time *from );