diff --git a/app/src/main/java/org/fdroid/fdroid/views/ManageReposActivity.java b/app/src/main/java/org/fdroid/fdroid/views/ManageReposActivity.java
index fe579d57d..926fd7367 100644
--- a/app/src/main/java/org/fdroid/fdroid/views/ManageReposActivity.java
+++ b/app/src/main/java/org/fdroid/fdroid/views/ManageReposActivity.java
@@ -785,7 +785,7 @@ public class ManageReposActivity extends AppCompatActivity
                         repo.userMirrors = new String[]{url};
                     } else {
                         int last = repo.userMirrors.length;
-                        repo.userMirrors = Arrays.copyOf(repo.userMirrors, last);
+                        repo.userMirrors = Arrays.copyOf(repo.userMirrors, last + 1);
                         repo.userMirrors[last] = url;
                     }
                     values.put(RepoTable.Cols.USER_MIRRORS, Utils.serializeCommaSeparatedString(repo.userMirrors));