diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index d62005edc0..b5784ad3c7 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c
@@ -8,6 +8,7 @@
 #include "parse-options.h"
 #include "commit-graph.h"
 #include "odb.h"
+#include "odb/source.h"
 #include "progress.h"
 #include "replace-object.h"
 #include "strbuf.h"
@@ -302,9 +303,19 @@ static int graph_write(int argc, const char **argv, const char *prefix,
 	}
 
 	if (opts.stdin_packs) {
-		while (strbuf_getline(&buf, stdin) != EOF)
-			string_list_append_nodup(&pack_indexes,
-						 strbuf_detach(&buf, NULL));
+		struct strbuf packname = STRBUF_INIT;
+		size_t dirlen;
+
+		strbuf_addf(&packname, "%s/pack/", source->path);
+		dirlen = packname.len;
+
+		while (strbuf_getline(&buf, stdin) != EOF) {
+			strbuf_setlen(&packname, dirlen);
+			strbuf_addbuf(&packname, &buf);
+			string_list_append(&pack_indexes, packname.buf);
+		}
+
+		strbuf_release(&packname);
 	} else if (opts.stdin_commits) {
 		oidset_init(&commits, 0);
 		if (opts.progress)
diff --git a/commit-graph.c b/commit-graph.c
index 983c11ce85..73814c1622 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -1936,12 +1936,8 @@ static int fill_oids_from_packs(struct write_commit_graph_context *ctx,
 {
 	uint32_t i;
 	struct strbuf progress_title = STRBUF_INIT;
-	struct strbuf packname = STRBUF_INIT;
-	int dirlen;
 	int ret = 0;
 
-	strbuf_addf(&packname, "%s/pack/", ctx->odb_source->path);
-	dirlen = packname.len;
 	if (ctx->report_progress) {
 		strbuf_addf(&progress_title,
 			    Q_("Finding commits for commit graph in %"PRIuMAX" pack",
@@ -1954,15 +1950,15 @@ static int fill_oids_from_packs(struct write_commit_graph_context *ctx,
 	}
 	for (i = 0; i < pack_indexes->nr; i++) {
 		struct packed_git *p;
-		strbuf_setlen(&packname, dirlen);
-		strbuf_addstr(&packname, pack_indexes->items[i].string);
-		p = add_packed_git(ctx->r, packname.buf, packname.len, 1);
+
+		p = add_packed_git(ctx->r, pack_indexes->items[i].string,
+				   strlen(pack_indexes->items[i].string), 1);
 		if (!p) {
-			ret = error(_("error adding pack %s"), packname.buf);
+			ret = error(_("error adding pack %s"), pack_indexes->items[i].string);
 			goto cleanup;
 		}
 		if (open_pack_index(p)) {
-			ret = error(_("error opening index for %s"), packname.buf);
+			ret = error(_("error opening index for %s"), pack_indexes->items[i].string);
 			close_pack(p);
 			free(p);
 			goto cleanup;
@@ -1976,7 +1972,6 @@ static int fill_oids_from_packs(struct write_commit_graph_context *ctx,
 cleanup:
 	stop_progress(&ctx->progress);
 	strbuf_release(&progress_title);
-	strbuf_release(&packname);
 
 	return ret;
 }