diff --git a/ed25519/ref10/ge.h b/ed25519/ref10/ge.h
index aec36af..1f01f3d 100644
--- a/ed25519/ref10/ge.h
+++ b/ed25519/ref10/ge.h
@@ -55,7 +55,8 @@ typedef unsigned char bytes32[32];
 #define ge_frombytes_negate_vartime crypto_sign_ed25519_ref10_ge_frombytes_negate_vartime
 #define ge_tobytes crypto_sign_ed25519_ref10_ge_tobytes
 #define ge_p3_tobytes crypto_sign_ed25519_ref10_ge_p3_tobytes
-#define ge_p3_batchtobytes_destructive crypto_sign_ed25519_ref10_ge_p3_batchtobytes_destructive
+#define ge_p3_batchtobytes_destructive_1 crypto_sign_ed25519_ref10_ge_p3_batchtobytes_destructive_1
+#define ge_p3_batchtobytes_destructive_finish crypto_sign_ed25519_ref10_ge_p3_batchtobytes_destructive_finish
 
 #define ge_p2_0 crypto_sign_ed25519_ref10_ge_p2_0
 #define ge_p3_0 crypto_sign_ed25519_ref10_ge_p3_0
@@ -76,7 +77,8 @@ typedef unsigned char bytes32[32];
 
 extern void ge_tobytes(unsigned char *,const ge_p2 *);
 extern void ge_p3_tobytes(unsigned char *,const ge_p3 *);
-extern void ge_p3_batchtobytes_destructive(bytes32 out[],const ge_p3 in[],fe *inz[],fe tmp[],size_t num);
+extern void ge_p3_batchtobytes_destructive_1(bytes32 out[],ge_p3 in[],fe *inz[],fe tmp[],size_t num);
+extern void ge_p3_batchtobytes_destructive_finish(bytes32 out,ge_p3 *unf);
 extern int ge_frombytes_negate_vartime(ge_p3 *,const unsigned char *);
 
 extern void ge_p2_0(ge_p2 *);
diff --git a/ed25519/ref10/ge_p3_batchtobytes.c b/ed25519/ref10/ge_p3_batchtobytes.c
index 19633ef..6b886c8 100644
--- a/ed25519/ref10/ge_p3_batchtobytes.c
+++ b/ed25519/ref10/ge_p3_batchtobytes.c
@@ -1,17 +1,23 @@
 #include "ge.h"
 
 // inz is ge_p3.Z pointer array. contents to .Zs will be overwritten
-void ge_p3_batchtobytes_destructive(bytes32 out[],const ge_p3 in[],fe *inz[],fe tmp[],size_t num)
+// NOTE: leaves in unfinished state
+void ge_p3_batchtobytes_destructive_1(bytes32 out[],ge_p3 in[],fe *inz[],fe tmp[],size_t num)
 {
-  fe x;
   fe y;
 
   fe_batchinvert(inz,tmp,inz,num);
 
   for (size_t i = 0;i < num;++i) {
-    fe_mul(x,in[i].X,*inz[i]);
-    fe_mul(y,in[i].Y,*inz[i]);
+    fe_mul(y,in[i].Y,in[i].Z);
     fe_tobytes(out[i],y);
-    out[i][31] ^= fe_isnegative(x) << 7;
   }
 }
+
+void ge_p3_batchtobytes_destructive_finish(bytes32 out,ge_p3 *unf)
+{
+  fe x;
+  // z of unfinished is inverted
+  fe_mul(x,unf->X,unf->Z);
+  out[31] ^= fe_isnegative(x) << 7;
+}
diff --git a/main.c b/main.c
index 945d1ff..472d6b4 100644
--- a/main.c
+++ b/main.c
@@ -581,7 +581,8 @@ initseed:
 			ge_add(&sum,&ge_public,&ge_eightpoint);
 			ge_p1p1_to_p3(&ge_public,&sum);
 		}
-		ge_p3_batchtobytes_destructive(pk_batch,ge_batch,batchgez,tmp_batch,BATCHNUM);
+		// NOTE: leaves unfinished
+		ge_p3_batchtobytes_destructive_1(pk_batch,ge_batch,batchgez,tmp_batch,BATCHNUM);
 
 #ifdef STATISTICS
 		st->numcalc.v += BATCHNUM;
@@ -602,6 +603,8 @@ initseed:
 					}
 				}
 				// found!
+				// finish it up
+				ge_p3_batchtobytes_destructive_finish(pk_batch[b],&ge_batch[b]);
 				// copy public key
 				memcpy(pk,pk_batch[b],PUBLIC_LEN);
 				// update secret key with counter