diff --git a/src/template/day.rs b/src/template/day.rs
--- a/src/template/day.rs
+++ b/src/template/day.rs
@@ -31,9 +31,12 @@ impl Day {
         Some(Self(day))
     }
 
-    // Not part of the public API
-    #[doc(hidden)]
-    pub const fn __new_unchecked(day: u8) -> Self {
+    /// Creates a new day without checking if it's in the valid range.
+    ///
+    /// # Safety
+    ///
+    /// Ensure that day is in range `1..=24`.
+    pub const unsafe fn new_unchecked(day: u8) -> Self {
         Self(day)
     }
 
@@ -146,7 +149,7 @@ macro_rules! day {
                 "`, expecting a value between 1 and 25"
             ),
         );
-        $crate::template::Day::__new_unchecked($day)
+        unsafe { $crate::template::Day::new_unchecked($day) }
     }};
 }