diff --git a/data.c b/data.c
index fcfd917..121407f 100644
--- a/data.c
+++ b/data.c
@@ -541,17 +541,15 @@ int index_in(const char *fn, const char *id)
 }
 
 
-int index_first(const char *fn, char *line, int size)
+int index_first(const char *fn, char md5[MD5_HEX_SIZE])
 /* reads the first entry of an index */
 {
     FILE *f;
     int ret = 0;
 
     if ((f = fopen(fn, "r")) != NULL) {
-        flock(fileno(f), LOCK_SH);
-
-        if (fgets(line, size, f) != NULL) {
-            line[MD5_HEX_SIZE - 1] = '\0';
+        if (fread(md5, MD5_HEX_SIZE, 1, f)) {
+            md5[MD5_HEX_SIZE - 1] = '\0';
             ret = 1;
         }
 
@@ -958,13 +956,13 @@ xs_list *object_announces(const char *id)
 }
 
 
-int object_parent(const char *md5, char *buf, int size)
+int object_parent(const char *md5, char parent[MD5_HEX_SIZE])
 /* returns the object parent, if any */
 {
     xs *fn = _object_fn_by_md5(md5, "object_parent");
 
     fn = xs_replace_i(fn, ".json", "_p.idx");
-    return index_first(fn, buf, size);
+    return index_first(fn, parent);
 }
 
 
@@ -1268,15 +1266,15 @@ xs_list *timeline_top_level(snac *snac, const xs_list *list)
 
     int c = 0;
     while (xs_list_next(list, &v, &c)) {
-        char line[256] = "";
+        char line[MD5_HEX_SIZE] = "";
 
         strncpy(line, v, sizeof(line));
 
         for (;;) {
-            char line2[256];
+            char line2[MD5_HEX_SIZE];
 
             /* if it doesn't have a parent, use this */
-            if (!object_parent(line, line2, sizeof(line2)))
+            if (!object_parent(line, line2))
                 break;
 
             /* well, there is a parent... but is it here? */
diff --git a/mastoapi.c b/mastoapi.c
index be477c3..8a6cbe6 100644
--- a/mastoapi.c
+++ b/mastoapi.c
@@ -2186,12 +2186,12 @@ int mastoapi_get_handler(const xs_dict *req, const char *q_path,
                         xs *des = xs_list_new();
                         xs_list *p;
                         const xs_str *v;
-                        char pid[64];
+                        char pid[MD5_HEX_SIZE];
 
                         /* build the [grand]parent list, moving up */
                         strncpy(pid, id, sizeof(pid));
 
-                        while (object_parent(pid, pid, sizeof(pid))) {
+                        while (object_parent(pid, pid)) {
                             xs *m2 = NULL;
 
                             if (valid_status(timeline_get_by_md5(&snac1, pid, &m2))) {
diff --git a/snac.h b/snac.h
index 78c39ef..280dc15 100644
--- a/snac.h
+++ b/snac.h
@@ -100,7 +100,7 @@ double f_ctime(const char *fn);
 int index_add_md5(const char *fn, const char *md5);
 int index_add(const char *fn, const char *id);
 int index_gc(const char *fn);
-int index_first(const char *fn, char *buf, int size);
+int index_first(const char *fn, char md5[MD5_HEX_SIZE]);
 int index_len(const char *fn);
 xs_list *index_list(const char *fn, int max);
 int index_desc_next(FILE *f, char md5[MD5_HEX_SIZE]);
@@ -130,7 +130,7 @@ int object_announces_len(const char *id);
 xs_list *object_children(const char *id);
 xs_list *object_likes(const char *id);
 xs_list *object_announces(const char *id);
-int object_parent(const char *id, char *buf, int size);
+int object_parent(const char *md5, char parent[MD5_HEX_SIZE]);
 
 int object_user_cache_add(snac *snac, const char *id, const char *cachedir);
 int object_user_cache_del(snac *snac, const char *id, const char *cachedir);