diff --git a/libminijail.c b/libminijail.c
index c7b5738..d492522 100644
--- a/libminijail.c
+++ b/libminijail.c
@@ -195,8 +195,8 @@
 	j->flags.gid = 1;
 }
 
-int API minijail_set_supplementary_gids(struct minijail *j, size_t size,
-					const gid_t *list)
+void API minijail_set_supplementary_gids(struct minijail *j, size_t size,
+					 const gid_t *list)
 {
 	size_t i;
 
@@ -208,7 +208,7 @@
 		j->suppl_gid_list = NULL;
 		j->suppl_gid_count = 0;
 		j->flags.suppl_gids = 1;
-		return 0;
+		return;
 	}
 
 	/* Copy the gid_t array. */
@@ -221,7 +221,6 @@
 	}
 	j->suppl_gid_count = size;
 	j->flags.suppl_gids = 1;
-	return 0;
 }
 
 int API minijail_change_user(struct minijail *j, const char *user)
diff --git a/libminijail.h b/libminijail.h
index ecc385a..fdd0d93 100644
--- a/libminijail.h
+++ b/libminijail.h
@@ -41,8 +41,8 @@
 void minijail_change_uid(struct minijail *j, uid_t uid);
 void minijail_change_gid(struct minijail *j, gid_t gid);
 /* Copies |list|. */
-int minijail_set_supplementary_gids(struct minijail *j, size_t size,
-				    const gid_t *list);
+void minijail_set_supplementary_gids(struct minijail *j, size_t size,
+				     const gid_t *list);
 /* Stores user to change to and copies |user| for internal consistency. */
 int minijail_change_user(struct minijail *j, const char *user);
 /* Does not take ownership of |group|. */