diff --git a/include/n2n.h b/include/n2n.h
index 9da119d..21b5ea2 100644
--- a/include/n2n.h
+++ b/include/n2n.h
@@ -150,8 +150,6 @@
 
 /* ************************************** */
 
-#include "tf.h"
-
 #ifndef TRACE_ERROR
 #define TRACE_ERROR       0
 #define TRACE_WARNING     1
diff --git a/include/tf.h b/include/tf.h
index 5f13f76..d2d0a65 100644
--- a/include/tf.h
+++ b/include/tf.h
@@ -51,11 +51,8 @@
 #define TF_H
 
 
-#include <stdint.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include "portable_endian.h"
+#include <stdint.h>  // for uint32_t
+#include <stdlib.h>  // for size_t
 
 
 #define TF_BLOCK_SIZE     16
diff --git a/src/tf.c b/src/tf.c
index 793c527..288ea84 100644
--- a/src/tf.c
+++ b/src/tf.c
@@ -48,6 +48,8 @@
 
 
 #include "tf.h"
+#include <endian.h>  // for le32toh, htole32
+#include <string.h>  // for memcpy
 
 
 const uint8_t RS[4][8] = { { 0x01, 0xA4, 0x55, 0x87, 0x5A, 0x58, 0xDB, 0x9E, },
diff --git a/src/transform_tf.c b/src/transform_tf.c
index e6ae404..f92ff92 100644
--- a/src/transform_tf.c
+++ b/src/transform_tf.c
@@ -20,6 +20,7 @@
 #include "n2n.h"             // for n2n_trans_op_t, traceEvent, TRACE_ERROR
 #include "pearson.h"         // for pearson_hash_256
 #include "random_numbers.h"  // for n2n_rand
+#include "tf.h"              // for TF_BLOCK_SIZE, tf_cbc_decrypt, tf_cbc_en...
 
 
 // size of random value prepended to plaintext defaults to TF_BLOCK_SIZE;