diff --git a/src/ssb.c b/src/ssb.c
index 618f92d6..1178a792 100644
--- a/src/ssb.c
+++ b/src/ssb.c
@@ -1135,8 +1135,8 @@ void tf_ssb_append_message(tf_ssb_t* ssb, JSValue message)
 	JS_SetPropertyStr(context, root, "author", authorstr);
 	JS_SetPropertyStr(context, root, "sequence", JS_NewInt64(context, previous_sequence + 1));
 
-	time_t now = time(NULL);
-	JS_SetPropertyStr(context, root, "timestamp", JS_NewInt64(context, now * 1000));
+	int64_t now = (int64_t)time(NULL);
+	JS_SetPropertyStr(context, root, "timestamp", JS_NewInt64(context, now * 1000LL));
 	JSValue hashstr = JS_NewString(context, "sha256");
 	JS_SetPropertyStr(context, root, "hash", hashstr);
 	JSValue content = JS_DupValue(context, message);