--- a/src/objstore/dirblock.c	Tue Mar 31 11:09:07 2020 -0400
+++ b/src/objstore/dirblock.c	Tue Mar 31 11:56:02 2020 -0400
@@ -143,6 +143,24 @@
 	return buffer_truncate(buf, DIR_BLOCK_SIZE);
 }
 
+static ssize_t __find_dirent(struct dirblock *block, const char *name)
+{
+	const size_t namelen = strlen(name);
+	size_t i;
+
+	for (i = 0; i < block->ndirents; i++) {
+		if (namelen != block->entries[i].dirent.namelen)
+			continue;
+
+		if (strncmp(name, block->entries[i].name, namelen))
+			continue;
+
+		return i;
+	}
+
+	return -ENOENT;
+}
+
 int dirblock_add_dirent(struct dirblock *block, const char *name,
 			const struct ndirent_tgt *tgt)
 {
@@ -150,12 +168,18 @@
 	uint8_t tgtrawbuf[128];
 	struct buffer tgtbuf;
 	size_t space_needed;
-	int idx;
-	int ret;
+	ssize_t ret;
+	size_t idx;
 
 	if (namelen > MAX_NAME_LEN)
 		return -ENAMETOOLONG;
 
+	ret = __find_dirent(block, name);
+	if (ret >= 0)
+		return -EEXIST;
+	if (ret != -ENOENT)
+		return ret;
+
 	buffer_init_static(&tgtbuf, tgtrawbuf, sizeof(tgtrawbuf), true);
 	VERIFY0(buffer_truncate(&tgtbuf, 0));