diff --git a/src/wp-includes/locale.php b/src/wp-includes/locale.php
index 1319c49dae..ded33782ba 100644
--- a/src/wp-includes/locale.php
+++ b/src/wp-includes/locale.php
@@ -105,19 +105,14 @@ class WP_Locale {
 		$this->weekday[5] = /* translators: weekday */ __('Friday');
 		$this->weekday[6] = /* translators: weekday */ __('Saturday');
 
-		// The first letter of each day. The _%day%_initial suffix is a hack to make
-		// sure the day initials are unique.
-		$this->weekday_initial[__('Sunday')]    = /* translators: one-letter abbreviation of the weekday */ __('S_Sunday_initial');
-		$this->weekday_initial[__('Monday')]    = /* translators: one-letter abbreviation of the weekday */ __('M_Monday_initial');
-		$this->weekday_initial[__('Tuesday')]   = /* translators: one-letter abbreviation of the weekday */ __('T_Tuesday_initial');
-		$this->weekday_initial[__('Wednesday')] = /* translators: one-letter abbreviation of the weekday */ __('W_Wednesday_initial');
-		$this->weekday_initial[__('Thursday')]  = /* translators: one-letter abbreviation of the weekday */ __('T_Thursday_initial');
-		$this->weekday_initial[__('Friday')]    = /* translators: one-letter abbreviation of the weekday */ __('F_Friday_initial');
-		$this->weekday_initial[__('Saturday')]  = /* translators: one-letter abbreviation of the weekday */ __('S_Saturday_initial');
-
-		foreach ($this->weekday_initial as $weekday_ => $weekday_initial_) {
-			$this->weekday_initial[$weekday_] = preg_replace('/_.+_initial$/', '', $weekday_initial_);
-		}
+		// The first letter of each day.
+		$this->weekday_initial[ __( 'Sunday' ) ]    = /* translators: one-letter abbreviation of the weekday */ _x( 'S', 'Sunday initial' );
+		$this->weekday_initial[ __( 'Monday' ) ]    = /* translators: one-letter abbreviation of the weekday */ _x( 'M', 'Monday initial' );
+		$this->weekday_initial[ __( 'Tuesday' ) ]   = /* translators: one-letter abbreviation of the weekday */ _x( 'T', 'Tuesday initial' );
+		$this->weekday_initial[ __( 'Wednesday' ) ] = /* translators: one-letter abbreviation of the weekday */ _x( 'W', 'Wednesday initial' );
+		$this->weekday_initial[ __( 'Thursday' ) ]  = /* translators: one-letter abbreviation of the weekday */ _x( 'T', 'Thursday initial' );
+		$this->weekday_initial[ __( 'Friday' ) ]    = /* translators: one-letter abbreviation of the weekday */ _x( 'F', 'Friday initial' );
+		$this->weekday_initial[ __( 'Saturday' ) ]  = /* translators: one-letter abbreviation of the weekday */ _x( 'S', 'Saturday initial' );
 
 		// Abbreviations for each day.
 		$this->weekday_abbrev[__('Sunday')]    = /* translators: three-letter abbreviation of the weekday */ __('Sun');
@@ -142,24 +137,19 @@ class WP_Locale {
 		$this->month['11'] = /* translators: month name */ __('November');
 		$this->month['12'] = /* translators: month name */ __('December');
 
-		// Abbreviations for each month. Uses the same hack as above to get around the
-		// 'May' duplication.
-		$this->month_abbrev[__('January')] = /* translators: three-letter abbreviation of the month */ __('Jan_January_abbreviation');
-		$this->month_abbrev[__('February')] = /* translators: three-letter abbreviation of the month */ __('Feb_February_abbreviation');
-		$this->month_abbrev[__('March')] = /* translators: three-letter abbreviation of the month */ __('Mar_March_abbreviation');
-		$this->month_abbrev[__('April')] = /* translators: three-letter abbreviation of the month */ __('Apr_April_abbreviation');
-		$this->month_abbrev[__('May')] = /* translators: three-letter abbreviation of the month */ __('May_May_abbreviation');
-		$this->month_abbrev[__('June')] = /* translators: three-letter abbreviation of the month */ __('Jun_June_abbreviation');
-		$this->month_abbrev[__('July')] = /* translators: three-letter abbreviation of the month */ __('Jul_July_abbreviation');
-		$this->month_abbrev[__('August')] = /* translators: three-letter abbreviation of the month */ __('Aug_August_abbreviation');
-		$this->month_abbrev[__('September')] = /* translators: three-letter abbreviation of the month */ __('Sep_September_abbreviation');
-		$this->month_abbrev[__('October')] = /* translators: three-letter abbreviation of the month */ __('Oct_October_abbreviation');
-		$this->month_abbrev[__('November')] = /* translators: three-letter abbreviation of the month */ __('Nov_November_abbreviation');
-		$this->month_abbrev[__('December')] = /* translators: three-letter abbreviation of the month */ __('Dec_December_abbreviation');
-
-		foreach ($this->month_abbrev as $month_ => $month_abbrev_) {
-			$this->month_abbrev[$month_] = preg_replace('/_.+_abbreviation$/', '', $month_abbrev_);
-		}
+		// Abbreviations for each month.
+		$this->month_abbrev[ __( 'January' ) ]   = /* translators: three-letter abbreviation of the month */ _x( 'Jan', 'January abbreviation' );
+		$this->month_abbrev[ __( 'February' ) ]  = /* translators: three-letter abbreviation of the month */ _x( 'Feb', 'February abbreviation' );
+		$this->month_abbrev[ __( 'March' ) ]     = /* translators: three-letter abbreviation of the month */ _x( 'Mar', 'March abbreviation' );
+		$this->month_abbrev[ __( 'April' ) ]     = /* translators: three-letter abbreviation of the month */ _x( 'Apr', 'April abbreviation' );
+		$this->month_abbrev[ __( 'May' ) ]       = /* translators: three-letter abbreviation of the month */ _x( 'May', 'May abbreviation' );
+		$this->month_abbrev[ __( 'June' ) ]      = /* translators: three-letter abbreviation of the month */ _x( 'Jun', 'June abbreviation' );
+		$this->month_abbrev[ __( 'July' ) ]      = /* translators: three-letter abbreviation of the month */ _x( 'Jul', 'July abbreviation' );
+		$this->month_abbrev[ __( 'August' ) ]    = /* translators: three-letter abbreviation of the month */ _x( 'Aug', 'August abbreviation' );
+		$this->month_abbrev[ __( 'September' ) ] = /* translators: three-letter abbreviation of the month */ _x( 'Sep', 'September abbreviation' );
+		$this->month_abbrev[ __( 'October' ) ]   = /* translators: three-letter abbreviation of the month */ _x( 'Oct', 'October abbreviation' );
+		$this->month_abbrev[ __( 'November' ) ]  = /* translators: three-letter abbreviation of the month */ _x( 'Nov', 'November abbreviation' );
+		$this->month_abbrev[ __( 'December' ) ]  = /* translators: three-letter abbreviation of the month */ _x( 'Dec', 'December abbreviation' );
 
 		// The Meridiems
 		$this->meridiem['am'] = __('am');