diff --git a/blkmaker_jansson.c b/blkmaker_jansson.c
index 06c97b3..643cf13 100644
--- a/blkmaker_jansson.c
+++ b/blkmaker_jansson.c
@@ -174,8 +174,10 @@ const char *blktmpl_add_jansson(blktemplate_t *tmpl, json_t *json, time_t time_r
 	GETNUM(height);
 	GETHEX(previousblockhash, prevblk);
 	my_flip(tmpl->prevblk, 32);
-	GETNUM(sigoplimit);
-	GETNUM(sizelimit);
+	if (json_object_get(json, "sigoplimit"))
+		GETNUM(sigoplimit);
+	if (json_object_get(json, "sizelimit"))
+		GETNUM(sizelimit);
 	GETNUM(version);
 	
 	if ((v = json_object_get(json, "coinbasevalue")) && json_is_number(v))
diff --git a/blktemplate.c b/blktemplate.c
index 2f69141..348f5db 100644
--- a/blktemplate.c
+++ b/blktemplate.c
@@ -1,5 +1,6 @@
 #define _BSD_SOURCE
 
+#include <limits.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
@@ -45,6 +46,9 @@ blktemplate_t *blktmpl_create() {
 	blktemplate_t *tmpl;
 	tmpl = calloc(1, sizeof(*tmpl));
 	
+	tmpl->sigoplimit = USHRT_MAX;
+	tmpl->sizelimit = ULONG_MAX;
+	
 	tmpl->maxtime = 0xffffffff;
 	tmpl->maxtimeoff = 0x7fff;
 	tmpl->mintimeoff = -0x7fff;