diff --git a/src/uu/uniq/src/uniq.rs b/src/uu/uniq/src/uniq.rs
index d947166fecb..d648424fc25 100644
--- a/src/uu/uniq/src/uniq.rs
+++ b/src/uu/uniq/src/uniq.rs
@@ -334,6 +334,8 @@ pub fn uu_app<'a>() -> Command<'a> {
                 .value_name("group-method")
                 .min_values(0)
                 .max_values(1)
+                .default_missing_value("separate")
+                .require_equals(true)
                 .conflicts_with_all(&[
                     options::REPEATED,
                     options::ALL_REPEATED,