diff --git a/src/components/calendar.rs b/src/components/calendar.rs
index 8091557a..aa4ab29c 100644
--- a/src/components/calendar.rs
+++ b/src/components/calendar.rs
@@ -8,6 +8,7 @@ use alloc::string::{String, ToString};
 use alloc::vec::Vec;
 use core::str::FromStr;
 
+use crate::parsers::parse_date_time;
 use crate::{
     components::{
         duration::{DateDuration, TimeDuration},
@@ -190,13 +191,21 @@ impl Calendar {
 impl FromStr for Calendar {
     type Err = TemporalError;
 
+    // 13.39 ParseTemporalCalendarString ( string )
     fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let mut cal_str = s;
+        if let Ok(record) = parse_date_time(s) {
+            if let Some(calendar) = record.calendar {
+                cal_str = calendar;
+            }
+        }
+
         // NOTE(nekesss): Catch the iso identifier here, as `iso8601` is not a valid ID below.
-        if s == "iso8601" {
+        if cal_str.to_lowercase() == "iso8601" {
             return Ok(Self::default());
         }
 
-        let Some(cal) = AnyCalendarKind::get_for_bcp47_string(s) else {
+        let Some(cal) = AnyCalendarKind::get_for_bcp47_string(cal_str) else {
             return Err(TemporalError::range().with_message("Not a builtin calendar."));
         };
 
@@ -322,6 +331,7 @@ impl Calendar {
                 resolved_fields.day,
                 self.clone(),
                 overflow,
+                None,
             );
         }
 
diff --git a/src/components/month_day.rs b/src/components/month_day.rs
index 31b7ead8..bca98791 100644
--- a/src/components/month_day.rs
+++ b/src/components/month_day.rs
@@ -36,9 +36,11 @@ impl PlainMonthDay {
         day: i32,
         calendar: Calendar,
         overflow: ArithmeticOverflow,
+        ref_year: Option<i32>,
     ) -> TemporalResult<Self> {
+        let ry = ref_year.unwrap_or(1972);
         // 1972 is the first leap year in the Unix epoch (needed to cover all dates)
-        let iso = IsoDate::new_with_overflow(1972, month, day, overflow)?;
+        let iso = IsoDate::new_with_overflow(ry, month, day, overflow)?;
         Ok(Self::new_unchecked(iso, calendar))
     }
 
@@ -56,6 +58,13 @@ impl PlainMonthDay {
         self.iso.month
     }
 
+    // returns the iso year value of `MonthDay`.
+    #[inline]
+    #[must_use]
+    pub fn iso_year(&self) -> i32 {
+        self.iso.year
+    }
+
     /// Returns the string identifier for the current calendar used.
     #[inline]
     #[must_use]
@@ -108,6 +117,7 @@ impl FromStr for PlainMonthDay {
             date.day.into(),
             Calendar::from_str(calendar)?,
             ArithmeticOverflow::Reject,
+            None,
         )
     }
 }
diff --git a/src/parsers.rs b/src/parsers.rs
index e2096cc4..a4e5f122 100644
--- a/src/parsers.rs
+++ b/src/parsers.rs
@@ -127,18 +127,8 @@ pub(crate) fn parse_year_month(source: &str) -> TemporalResult<IxdtfParseRecord>
 #[inline]
 pub(crate) fn parse_month_day(source: &str) -> TemporalResult<IxdtfParseRecord> {
     let md_record = parse_ixdtf(source, ParseVariant::MonthDay);
-
-    if let Ok(md) = md_record {
-        return Ok(md);
-    }
-
-    let dt_parse = parse_ixdtf(source, ParseVariant::DateTime);
-
-    match dt_parse {
-        Ok(dt) => Ok(dt),
-        // Format and return the error from parsing YearMonth.
-        _ => md_record.map_err(|e| TemporalError::range().with_message(format!("{e}"))),
-    }
+    // Error needs to be a RangeError
+    md_record.map_err(|e| TemporalError::range().with_message(format!("{e}")))
 }
 
 #[inline]