diff --git a/src/libbpf.c b/src/libbpf.c
index 60ec969..9f42120 100644
--- a/src/libbpf.c
+++ b/src/libbpf.c
@@ -1221,7 +1221,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 
 	if (!obj->efile.strtabidx || obj->efile.strtabidx >= idx) {
 		pr_warning("Corrupted ELF file: index of strtab invalid\n");
-		return LIBBPF_ERRNO__FORMAT;
+		return -LIBBPF_ERRNO__FORMAT;
 	}
 	if (btf_data) {
 		obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);