diff --git a/src/uu/du/src/du.rs b/src/uu/du/src/du.rs
index 20409f621b7..a199dc84adf 100644
--- a/src/uu/du/src/du.rs
+++ b/src/uu/du/src/du.rs
@@ -1288,6 +1288,7 @@ pub fn uu_app() -> Command {
                 .short('a')
                 .long(options::ALL)
                 .help(translate!("du-help-all"))
+                .conflicts_with(options::SUMMARIZE)
                 .action(ArgAction::SetTrue),
         )
         .arg(
diff --git a/tests/by-util/test_du.rs b/tests/by-util/test_du.rs
index 40fd410f715..5aa8d904ea5 100644
--- a/tests/by-util/test_du.rs
+++ b/tests/by-util/test_du.rs
@@ -84,6 +84,11 @@ fn du_basics(s: &str) {
     assert_eq!(s, answer);
 }
 
+#[test]
+fn test_all_summarize() {
+    new_ucmd!().arg("-a").arg("-s").fails_with_code(1); //clap provided message
+}
+
 #[test]
 fn test_invalid_arg() {
     new_ucmd!().arg("--definitely-invalid").fails_with_code(1);