diff --git a/blkmaker.c b/blkmaker.c
index 1bb6e28..ac5fee5 100644
--- a/blkmaker.c
+++ b/blkmaker.c
@@ -41,16 +41,14 @@ bool _blkmk_dblsha256(void *hash, const void *data, size_t datasz) {
 
 #define dblsha256 _blkmk_dblsha256
 
-uint64_t blkmk_init_generation2(blktemplate_t *tmpl, void *script, size_t scriptsz, bool *out_newcb) {
-	if (tmpl->cbtxn)
+uint64_t blkmk_init_generation3(blktemplate_t * const tmpl, const void * const script, const size_t scriptsz, bool * const inout_newcb) {
+	if (tmpl->cbtxn && !(*inout_newcb && (tmpl->mutations & BMM_GENERATE)))
 	{
-		if (out_newcb)
-			*out_newcb = false;
+		*inout_newcb = false;
 		return 0;
 	}
 	
-	if (out_newcb)
-		*out_newcb = true;
+	*inout_newcb = true;
 	
 	size_t datasz = 62 + sizeof(blkheight_t) + scriptsz;
 	unsigned char *data = malloc(datasz);
@@ -101,6 +99,11 @@ uint64_t blkmk_init_generation2(blktemplate_t *tmpl, void *script, size_t script
 	txn->data = data;
 	txn->datasz = off;
 	
+	if (tmpl->cbtxn)
+	{
+		_blktxn_free(tmpl->cbtxn);
+		free(tmpl->cbtxn);
+	}
 	tmpl->cbtxn = txn;
 	
 	tmpl->mutations |= BMM_CBAPPEND | BMM_CBSET | BMM_GENERATE;
@@ -108,6 +111,14 @@ uint64_t blkmk_init_generation2(blktemplate_t *tmpl, void *script, size_t script
 	return tmpl->cbvalue;
 }
 
+uint64_t blkmk_init_generation2(blktemplate_t *tmpl, void *script, size_t scriptsz, bool *out_newcb) {
+	bool tmp;
+	if (!out_newcb)
+		out_newcb = &tmp;
+	*out_newcb = false;
+	blkmk_init_generation3(tmpl, script, scriptsz, out_newcb);
+}
+
 uint64_t blkmk_init_generation(blktemplate_t *tmpl, void *script, size_t scriptsz) {
 	return blkmk_init_generation2(tmpl, script, scriptsz, NULL);
 }
diff --git a/blkmaker.h b/blkmaker.h
index 83b6025..f9d7827 100644
--- a/blkmaker.h
+++ b/blkmaker.h
@@ -14,6 +14,7 @@ extern bool (*blkmk_sha256_impl)(void *hash_out, const void *data, size_t datasz
 
 extern uint64_t blkmk_init_generation(blktemplate_t *, void *script, size_t scriptsz);
 extern uint64_t blkmk_init_generation2(blktemplate_t *, void *script, size_t scriptsz, bool *out_newcb);
+extern uint64_t blkmk_init_generation3(blktemplate_t *, const void *script, size_t scriptsz, bool *inout_newcb);
 extern ssize_t blkmk_append_coinbase_safe(blktemplate_t *, const void *append, size_t appendsz);
 extern bool _blkmk_extranonce(blktemplate_t *tmpl, void *vout, unsigned int workid, size_t *offs);
 extern size_t blkmk_get_data(blktemplate_t *, void *buf, size_t bufsz, time_t usetime, int16_t *out_expire, unsigned int *out_dataid);
diff --git a/blktemplate.c b/blktemplate.c
index ea4c87d..1dd61a2 100644
--- a/blktemplate.c
+++ b/blktemplate.c
@@ -93,12 +93,12 @@ bool blktmpl_get_submitold(blktemplate_t *tmpl) {
 	return tmpl->submitold;
 }
 
-static
-void blktxn_free(struct blktxn_t *bt) {
+void _blktxn_free(struct blktxn_t *bt) {
 	free(bt->data);
 	free(bt->hash);
 	free(bt->depends);
 }
+#define blktxn_free  _blktxn_free
 
 void blktmpl_free(blktemplate_t *tmpl) {
 	for (unsigned long i = 0; i < tmpl->txncount; ++i)
diff --git a/private.h b/private.h
index 02a298b..33e4c7f 100644
--- a/private.h
+++ b/private.h
@@ -7,6 +7,9 @@
 // blkmaker.c
 extern bool _blkmk_dblsha256(void *hash, const void *data, size_t datasz);
 
+// blktemplate.c
+extern void _blktxn_free(struct blktxn_t *);
+
 // hex.c
 extern void _blkmk_bin2hex(char *out, const void *data, size_t datasz);
 extern bool _blkmk_hex2bin(void *o, const char *x, size_t len);