diff --git a/crypto_kem/ntruhps2048509/META.yml b/crypto_kem/ntruhps2048509/META.yml
index e04dcd86..b261c05f 100644
--- a/crypto_kem/ntruhps2048509/META.yml
+++ b/crypto_kem/ntruhps2048509/META.yml
@@ -23,9 +23,9 @@ auxiliary-submitters:
   - Zhenfei Zhang
 implementations:
     - name: clean
-      version: https://github.com/jschanck/ntru/tree/b4b08d67 reference implementation
+      version: https://github.com/jschanck/ntru/tree/a6b42aac reference implementation
     - name: avx2
-      version: https://github.com/jschanck/ntru/tree/b4b08d67 avx2 implementation
+      version: https://github.com/jschanck/ntru/tree/a6b42aac avx2 implementation
       supported_platforms:
           - architecture: x86_64
             operating_systems:
diff --git a/crypto_kem/ntruhps2048509/clean/poly.h b/crypto_kem/ntruhps2048509/clean/poly.h
index 66830976..30816b96 100644
--- a/crypto_kem/ntruhps2048509/clean/poly.h
+++ b/crypto_kem/ntruhps2048509/clean/poly.h
@@ -4,6 +4,7 @@
 #include "params.h"
 
 #include <stdint.h>
+#include <stddef.h>
 
 #define MODQ(X) ((X) & (NTRU_Q-1))
 
diff --git a/crypto_kem/ntruhps2048509/clean/poly_r2_inv.c b/crypto_kem/ntruhps2048509/clean/poly_r2_inv.c
index bfcb974c..82e3164d 100644
--- a/crypto_kem/ntruhps2048509/clean/poly_r2_inv.c
+++ b/crypto_kem/ntruhps2048509/clean/poly_r2_inv.c
@@ -9,8 +9,8 @@ static inline int16_t both_negative_mask(int16_t x, int16_t y) {
 
 void PQCLEAN_NTRUHPS2048509_CLEAN_poly_R2_inv(poly *r, const poly *a) {
     poly f, g, v, w;
-    int16_t i, loop, delta;
-    int16_t sign, swap, t;
+    size_t i, loop;
+    int16_t delta, sign, swap, t;
 
     for (i = 0; i < NTRU_N; ++i) {
         v.coeffs[i] = 0;
diff --git a/crypto_kem/ntruhps2048509/clean/poly_s3_inv.c b/crypto_kem/ntruhps2048509/clean/poly_s3_inv.c
index 32cd39ca..6887e7f6 100644
--- a/crypto_kem/ntruhps2048509/clean/poly_s3_inv.c
+++ b/crypto_kem/ntruhps2048509/clean/poly_s3_inv.c
@@ -17,8 +17,8 @@ static inline int16_t both_negative_mask(int16_t x, int16_t y) {
 
 void PQCLEAN_NTRUHPS2048509_CLEAN_poly_S3_inv(poly *r, const poly *a) {
     poly f, g, v, w;
-    int16_t i, loop, delta;
-    int16_t sign, swap, t;
+    size_t i, loop;
+    int16_t delta, sign, swap, t;
 
     for (i = 0; i < NTRU_N; ++i) {
         v.coeffs[i] = 0;
diff --git a/crypto_kem/ntruhps2048677/META.yml b/crypto_kem/ntruhps2048677/META.yml
index 90e464c5..5281fe72 100644
--- a/crypto_kem/ntruhps2048677/META.yml
+++ b/crypto_kem/ntruhps2048677/META.yml
@@ -23,9 +23,9 @@ auxiliary-submitters:
   - Zhenfei Zhang
 implementations:
     - name: clean
-      version: https://github.com/jschanck/ntru/tree/b4b08d67 reference implementation
+      version: https://github.com/jschanck/ntru/tree/a6b42aac reference implementation
     - name: avx2
-      version: https://github.com/jschanck/ntru/tree/b4b08d67 avx2 implementation
+      version: https://github.com/jschanck/ntru/tree/a6b42aac avx2 implementation
       supported_platforms:
           - architecture: x86_64
             operating_systems:
diff --git a/crypto_kem/ntruhps2048677/clean/poly.h b/crypto_kem/ntruhps2048677/clean/poly.h
index 97e2f6e1..6b6d381f 100644
--- a/crypto_kem/ntruhps2048677/clean/poly.h
+++ b/crypto_kem/ntruhps2048677/clean/poly.h
@@ -4,6 +4,7 @@
 #include "params.h"
 
 #include <stdint.h>
+#include <stddef.h>
 
 #define MODQ(X) ((X) & (NTRU_Q-1))
 
diff --git a/crypto_kem/ntruhps2048677/clean/poly_r2_inv.c b/crypto_kem/ntruhps2048677/clean/poly_r2_inv.c
index 2bc45e07..3e1e1c76 100644
--- a/crypto_kem/ntruhps2048677/clean/poly_r2_inv.c
+++ b/crypto_kem/ntruhps2048677/clean/poly_r2_inv.c
@@ -9,8 +9,8 @@ static inline int16_t both_negative_mask(int16_t x, int16_t y) {
 
 void PQCLEAN_NTRUHPS2048677_CLEAN_poly_R2_inv(poly *r, const poly *a) {
     poly f, g, v, w;
-    int16_t i, loop, delta;
-    int16_t sign, swap, t;
+    size_t i, loop;
+    int16_t delta, sign, swap, t;
 
     for (i = 0; i < NTRU_N; ++i) {
         v.coeffs[i] = 0;
diff --git a/crypto_kem/ntruhps2048677/clean/poly_s3_inv.c b/crypto_kem/ntruhps2048677/clean/poly_s3_inv.c
index 00c0ad8f..46f6ece1 100644
--- a/crypto_kem/ntruhps2048677/clean/poly_s3_inv.c
+++ b/crypto_kem/ntruhps2048677/clean/poly_s3_inv.c
@@ -17,8 +17,8 @@ static inline int16_t both_negative_mask(int16_t x, int16_t y) {
 
 void PQCLEAN_NTRUHPS2048677_CLEAN_poly_S3_inv(poly *r, const poly *a) {
     poly f, g, v, w;
-    int16_t i, loop, delta;
-    int16_t sign, swap, t;
+    size_t i, loop;
+    int16_t delta, sign, swap, t;
 
     for (i = 0; i < NTRU_N; ++i) {
         v.coeffs[i] = 0;
diff --git a/crypto_kem/ntruhps4096821/META.yml b/crypto_kem/ntruhps4096821/META.yml
index 2621f03f..651f063d 100644
--- a/crypto_kem/ntruhps4096821/META.yml
+++ b/crypto_kem/ntruhps4096821/META.yml
@@ -23,9 +23,9 @@ auxiliary-submitters:
   - Zhenfei Zhang
 implementations:
     - name: clean
-      version: https://github.com/jschanck/ntru/tree/b4b08d67 reference implementation
+      version: https://github.com/jschanck/ntru/tree/a6b42aac reference implementation
     - name: avx2
-      version: https://github.com/jschanck/ntru/tree/b4b08d67 avx2 implementation
+      version: https://github.com/jschanck/ntru/tree/a6b42aac avx2 implementation
       supported_platforms:
           - architecture: x86_64
             operating_systems:
diff --git a/crypto_kem/ntruhps4096821/clean/poly.h b/crypto_kem/ntruhps4096821/clean/poly.h
index 851222ae..0d684313 100644
--- a/crypto_kem/ntruhps4096821/clean/poly.h
+++ b/crypto_kem/ntruhps4096821/clean/poly.h
@@ -4,6 +4,7 @@
 #include "params.h"
 
 #include <stdint.h>
+#include <stddef.h>
 
 #define MODQ(X) ((X) & (NTRU_Q-1))
 
diff --git a/crypto_kem/ntruhps4096821/clean/poly_r2_inv.c b/crypto_kem/ntruhps4096821/clean/poly_r2_inv.c
index 8d110d28..9da75ae0 100644
--- a/crypto_kem/ntruhps4096821/clean/poly_r2_inv.c
+++ b/crypto_kem/ntruhps4096821/clean/poly_r2_inv.c
@@ -9,8 +9,8 @@ static inline int16_t both_negative_mask(int16_t x, int16_t y) {
 
 void PQCLEAN_NTRUHPS4096821_CLEAN_poly_R2_inv(poly *r, const poly *a) {
     poly f, g, v, w;
-    int16_t i, loop, delta;
-    int16_t sign, swap, t;
+    size_t i, loop;
+    int16_t delta, sign, swap, t;
 
     for (i = 0; i < NTRU_N; ++i) {
         v.coeffs[i] = 0;
diff --git a/crypto_kem/ntruhps4096821/clean/poly_s3_inv.c b/crypto_kem/ntruhps4096821/clean/poly_s3_inv.c
index 35b38d8e..ac54d4f8 100644
--- a/crypto_kem/ntruhps4096821/clean/poly_s3_inv.c
+++ b/crypto_kem/ntruhps4096821/clean/poly_s3_inv.c
@@ -17,8 +17,8 @@ static inline int16_t both_negative_mask(int16_t x, int16_t y) {
 
 void PQCLEAN_NTRUHPS4096821_CLEAN_poly_S3_inv(poly *r, const poly *a) {
     poly f, g, v, w;
-    int16_t i, loop, delta;
-    int16_t sign, swap, t;
+    size_t i, loop;
+    int16_t delta, sign, swap, t;
 
     for (i = 0; i < NTRU_N; ++i) {
         v.coeffs[i] = 0;
diff --git a/crypto_kem/ntruhrss701/META.yml b/crypto_kem/ntruhrss701/META.yml
index 5df494e0..95866b90 100644
--- a/crypto_kem/ntruhrss701/META.yml
+++ b/crypto_kem/ntruhrss701/META.yml
@@ -23,9 +23,9 @@ auxiliary-submitters:
   - Zhenfei Zhang
 implementations:
     - name: clean
-      version: https://github.com/jschanck/ntru/tree/b4b08d67 reference implementation
+      version: https://github.com/jschanck/ntru/tree/a6b42aac reference implementation
     - name: avx2
-      version: https://github.com/jschanck/ntru/tree/b4b08d67 avx2 implementation
+      version: https://github.com/jschanck/ntru/tree/a6b42aac avx2 implementation
       supported_platforms:
           - architecture: x86_64
             operating_systems:
diff --git a/crypto_kem/ntruhrss701/clean/poly.h b/crypto_kem/ntruhrss701/clean/poly.h
index f41fb78e..40391362 100644
--- a/crypto_kem/ntruhrss701/clean/poly.h
+++ b/crypto_kem/ntruhrss701/clean/poly.h
@@ -4,6 +4,7 @@
 #include "params.h"
 
 #include <stdint.h>
+#include <stddef.h>
 
 #define MODQ(X) ((X) & (NTRU_Q-1))
 
diff --git a/crypto_kem/ntruhrss701/clean/poly_r2_inv.c b/crypto_kem/ntruhrss701/clean/poly_r2_inv.c
index 7d5ff25a..422deae6 100644
--- a/crypto_kem/ntruhrss701/clean/poly_r2_inv.c
+++ b/crypto_kem/ntruhrss701/clean/poly_r2_inv.c
@@ -9,8 +9,8 @@ static inline int16_t both_negative_mask(int16_t x, int16_t y) {
 
 void PQCLEAN_NTRUHRSS701_CLEAN_poly_R2_inv(poly *r, const poly *a) {
     poly f, g, v, w;
-    int16_t i, loop, delta;
-    int16_t sign, swap, t;
+    size_t i, loop;
+    int16_t delta, sign, swap, t;
 
     for (i = 0; i < NTRU_N; ++i) {
         v.coeffs[i] = 0;
diff --git a/crypto_kem/ntruhrss701/clean/poly_s3_inv.c b/crypto_kem/ntruhrss701/clean/poly_s3_inv.c
index 41bf0a77..d6ca4ee6 100644
--- a/crypto_kem/ntruhrss701/clean/poly_s3_inv.c
+++ b/crypto_kem/ntruhrss701/clean/poly_s3_inv.c
@@ -17,8 +17,8 @@ static inline int16_t both_negative_mask(int16_t x, int16_t y) {
 
 void PQCLEAN_NTRUHRSS701_CLEAN_poly_S3_inv(poly *r, const poly *a) {
     poly f, g, v, w;
-    int16_t i, loop, delta;
-    int16_t sign, swap, t;
+    size_t i, loop;
+    int16_t delta, sign, swap, t;
 
     for (i = 0; i < NTRU_N; ++i) {
         v.coeffs[i] = 0;