diff --git a/crates/oxide_builtins/src/temporal.rs b/crates/oxide_builtins/src/temporal.rs
index 2eb1d28b..d2066f58 100644
--- a/crates/oxide_builtins/src/temporal.rs
+++ b/crates/oxide_builtins/src/temporal.rs
@@ -4625,12 +4625,26 @@ pub fn plain_time_constructor<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResul
         }
         temporal_number_component(vm, raw)
     };
-    let hour = native_try!(get(1)) as u32;
-    let minute = native_try!(get(2)) as u32;
-    let second = native_try!(get(3)) as u32;
-    let ms = native_try!(get(4)) as u32;
-    let us = native_try!(get(5)) as u32;
-    let ns = native_try!(get(6)) as u32;
+    // 负值在 u32 转换前检查：截断后为负的整分量（含负分数整数化为负）须先抛错，
+    // 不能让 f64→u32 饱和把其静默归 0 而逃过范围检查。
+    let hour_value = native_try!(get(1));
+    let minute_value = native_try!(get(2));
+    let second_value = native_try!(get(3));
+    let ms_value = native_try!(get(4));
+    let us_value = native_try!(get(5));
+    let ns_value = native_try!(get(6));
+    if [hour_value, minute_value, second_value, ms_value, us_value, ns_value]
+        .iter()
+        .any(|value| *value < 0.0)
+    {
+        return NativeResult::Err(crate::error::create_range_error(vm, "invalid time component"));
+    }
+    let hour = hour_value as u32;
+    let minute = minute_value as u32;
+    let second = second_value as u32;
+    let ms = ms_value as u32;
+    let us = us_value as u32;
+    let ns = ns_value as u32;
     if !valid_plain_time(hour, minute, second, ms, us, ns) {
         return NativeResult::Err(crate::error::create_range_error(vm, "invalid time component"));
     }
diff --git a/crates/oxide_vm/tests/builtins_temporal_tests.rs b/crates/oxide_vm/tests/builtins_temporal_tests.rs
index 3347032a..31f68219 100644
--- a/crates/oxide_vm/tests/builtins_temporal_tests.rs
+++ b/crates/oxide_vm/tests/builtins_temporal_tests.rs
@@ -3817,6 +3817,32 @@ fn plain_time_ctor_number_component_rejects_and_undefined_default() {
     );
 }
 
+#[test]
+fn plain_time_ctor_negative_time_components_throw_range_error() {
+    let mut vm = Vm::new();
+    // 红形钉：六分量（时/分/秒/毫秒/微秒/纳秒）负值各一例均抛 RangeError，
+    // 消息复用既有范围错口径 "invalid time component"。
+    let r = eval(
+        &mut vm,
+        "(() => {
+           const kind = (fn) => { try { fn(); return 'no'; } catch (e) { return e.constructor.name + ':' + e.message; } };
+           return [
+             kind(() => new Temporal.PlainTime(-1, 0, 0, 0, 0, 0)),
+             kind(() => new Temporal.PlainTime(0, -1, 0, 0, 0, 0)),
+             kind(() => new Temporal.PlainTime(0, 0, -1, 0, 0, 0)),
+             kind(() => new Temporal.PlainTime(0, 0, 0, -1, 0, 0)),
+             kind(() => new Temporal.PlainTime(0, 0, 0, 0, -1, 0)),
+             kind(() => new Temporal.PlainTime(0, 0, 0, 0, 0, -1)),
+           ].join('|');
+         })()",
+    )
+    .unwrap();
+    assert_eq!(
+        str_val(&vm, r),
+        "RangeError:invalid time component|RangeError:invalid time component|RangeError:invalid time component|RangeError:invalid time component|RangeError:invalid time component|RangeError:invalid time component"
+    );
+}
+
 #[test]
 fn plain_date_time_ctor_undefined_time_components_default() {
     let mut vm = Vm::new();