diff --git a/common/test/run-json.c b/common/test/run-json.c
new file mode 100644
index 000000000..e599a0f59
--- /dev/null
+++ b/common/test/run-json.c
@@ -0,0 +1,45 @@
+#include "../json.c"
+#include <stdio.h>
+
+/* AUTOGENERATED MOCKS START */
+/* AUTOGENERATED MOCKS END */
+
+int main(void)
+{
+	struct json_result *result = new_json_result(NULL);
+	jsmntok_t *toks;
+	const jsmntok_t *x;
+	bool valid;
+	int i;
+	char *badstr = tal_arr(result, char, 256);
+	const char *str;
+
+	/* Fill with junk, and nul-terminate (256 -> 0) */
+	for (i = 1; i < 257; i++)
+		badstr[i-1] = i;
+
+	json_object_start(result, NULL);
+	json_add_string(result, "x", badstr);
+	json_object_end(result);
+
+	/* Parse back in, make sure nothing crazy. */
+	str = json_result_string(result);
+
+	toks = json_parse_input(str, strlen(str), &valid);
+	assert(valid);
+	assert(toks);
+
+	assert(toks[0].type == JSMN_OBJECT);
+	x = json_get_member(str, toks, "x");
+	assert(x);
+	assert(x->type == JSMN_STRING);
+	assert((x->end - x->start) == 255);
+	for (i = x->start; i < x->end; i++) {
+		assert(cisprint(str[i]));
+		assert(str[i] != '\\');
+		assert(str[i] != '"');
+		assert(str[i] == '?' || str[i] == badstr[i - x->start]);
+	}
+	tal_free(result);
+	return 0;
+}
diff --git a/lightningd/test/run-cryptomsg.c b/lightningd/test/run-cryptomsg.c
index 35126ede9..fead63c04 100644
--- a/lightningd/test/run-cryptomsg.c
+++ b/lightningd/test/run-cryptomsg.c
@@ -47,6 +47,8 @@ void dev_blackhole_fd(int fd UNNEEDED)
 /* Generated stub for dev_sabotage_fd */
 void dev_sabotage_fd(int fd UNNEEDED)
 { fprintf(stderr, "dev_sabotage_fd called!\n"); abort(); }
+/* Could not find declaration for secp256k1_ecdsa_recoverable_signature_parse_compact */
+/* Could not find declaration for secp256k1_ecdsa_recoverable_signature_serialize_compact */
 /* AUTOGENERATED MOCKS END */
 
 enum dev_disconnect dev_disconnect(int pkt_type)
diff --git a/lightningd/test/run-find_my_path.c b/lightningd/test/run-find_my_path.c
index 64c6ebc1c..13b673618 100644
--- a/lightningd/test/run-find_my_path.c
+++ b/lightningd/test/run-find_my_path.c
@@ -46,6 +46,8 @@ void populate_peer(struct lightningd *ld UNNEEDED, struct peer *peer UNNEEDED)
 /* Generated stub for register_opts */
 void register_opts(struct lightningd *ld UNNEEDED)
 { fprintf(stderr, "register_opts called!\n"); abort(); }
+/* Could not find declaration for secp256k1_ecdsa_recoverable_signature_parse_compact */
+/* Could not find declaration for secp256k1_ecdsa_recoverable_signature_serialize_compact */
 /* Generated stub for setup_color_and_alias */
 void setup_color_and_alias(struct lightningd *ld UNNEEDED)
 { fprintf(stderr, "setup_color_and_alias called!\n"); abort(); }