diff --git a/src/uu/uniq/src/uniq.rs b/src/uu/uniq/src/uniq.rs
index 4a7c86edf60..a54b4876c76 100644
--- a/src/uu/uniq/src/uniq.rs
+++ b/src/uu/uniq/src/uniq.rs
@@ -357,7 +357,9 @@ fn opt_parsed(opt_name: &str, matches: &ArgMatches) -> UResult<Option<usize>> {
         Some(arg_str) => match arg_str.parse::<usize>() {
             Ok(v) => Ok(Some(v)),
             Err(e) => match e.kind() {
-                IntErrorKind::PosOverflow => Ok(Some(usize::MAX)),
+                IntErrorKind::PosOverflow if arg_str.chars().all(|c| c.is_ascii_digit()) => {
+                    Ok(Some(usize::MAX))
+                }
                 _ => Err(USimpleError::new(
                     1,
                     translate!("uniq-error-invalid-argument", "opt_name" => opt_name, "arg" => arg_str.maybe_quote()),
diff --git a/tests/by-util/test_uniq.rs b/tests/by-util/test_uniq.rs
index 98d72cda27d..a622b543803 100644
--- a/tests/by-util/test_uniq.rs
+++ b/tests/by-util/test_uniq.rs
@@ -1351,3 +1351,32 @@ fn test_obsolete_skip_fields_not_read_after_double_dash() {
         .fails()
         .stderr_contains("-1");
 }
+
+#[test]
+fn test_overflowing_numeric_options_with_trailing_garbage_rejected() {
+    // Large values that overflow usize but have trailing non-digits must be rejected (issue #16122)
+    new_ucmd!()
+        .args(&["-f", "18446744073709551616x"])
+        .pipe_in("first\nsecond\nthird\n")
+        .fails_with_code(1)
+        .stderr_contains("Invalid argument");
+
+    new_ucmd!()
+        .args(&["-s", "18446744073709551616x"])
+        .pipe_in("first\nsecond\nthird\n")
+        .fails_with_code(1)
+        .stderr_contains("Invalid argument");
+
+    new_ucmd!()
+        .args(&["-w", "18446744073709551616x"])
+        .pipe_in("first\nsecond\nthird\n")
+        .fails_with_code(1)
+        .stderr_contains("Invalid argument");
+
+    // Purely numeric overflowing values remain accepted (clamped to usize::MAX)
+    new_ucmd!()
+        .args(&["-f", "18446744073709551616"])
+        .pipe_in("first\nsecond\nthird\n")
+        .succeeds()
+        .stdout_is("first\n");
+}