diff --git a/common/test/run-bolt12_decode.c b/common/test/run-bolt12_decode.c
index 5bbb6f7a1..e2fa5f0ca 100644
--- a/common/test/run-bolt12_decode.c
+++ b/common/test/run-bolt12_decode.c
@@ -195,7 +195,7 @@ int main(int argc, char *argv[])
 		size_t dlen;
 		struct json_escape *esc;
 
-		json_to_bool(json, json_get_member(json, t, "valid"), &valid);
+		assert(json_to_bool(json, json_get_member(json, t, "valid"), &valid));
 		strtok = json_get_member(json, t, "string");
 		esc = json_escape_string_(tmpctx, json + strtok->start,
 					  strtok->end - strtok->start);