diff --git a/phpBB/styles/prosilver/template/timezone.js b/phpBB/styles/prosilver/template/timezone.js
index af8206d12d..5e81a0bfdf 100644
--- a/phpBB/styles/prosilver/template/timezone.js
+++ b/phpBB/styles/prosilver/template/timezone.js
@@ -13,7 +13,7 @@ $(document).ready(
 );
 
 $(document).ready(
-	phpbb.timezonePreselectSelect($('#tz_select_date_suggest').attr('data-is-registration') == 'true')
+	phpbb.timezonePreselectSelect($('#tz_select_date_suggest').attr('timezone-preselect') == 'true')
 );
 
 })(jQuery); // Avoid conflicts with other libraries
diff --git a/phpBB/styles/prosilver/template/timezone_option.html b/phpBB/styles/prosilver/template/timezone_option.html
index 6f09f276ff..a77e82f9a1 100644
--- a/phpBB/styles/prosilver/template/timezone_option.html
+++ b/phpBB/styles/prosilver/template/timezone_option.html
@@ -6,7 +6,7 @@
 			<option value="">{L_SELECT_CURRENT_TIME}</option>
 			{S_TZ_DATE_OPTIONS}
 		</select>
-		<input type="button" id="tz_select_date_suggest" class="button2" style="display: none;" data-is-registration="<!-- IF S_TZ_PRESELECT -->true<!-- ELSE -->false<!-- ENDIF -->" data-l-suggestion="{L_TIMEZONE_DATE_SUGGESTION}" value="{L_TIMEZONE_DATE_SUGGESTION}" />
+		<input type="button" id="tz_select_date_suggest" class="button2" style="display: none;" timezone-preselect="<!-- IF S_TZ_PRESELECT -->true<!-- ELSE -->false<!-- ENDIF -->" data-l-suggestion="{L_TIMEZONE_DATE_SUGGESTION}" value="{L_TIMEZONE_DATE_SUGGESTION}" />
 	</dd>
 	<!-- ENDIF -->
 	<dd>
diff --git a/phpBB/styles/subsilver2/template/timezone.js b/phpBB/styles/subsilver2/template/timezone.js
index af8206d12d..5e81a0bfdf 100644
--- a/phpBB/styles/subsilver2/template/timezone.js
+++ b/phpBB/styles/subsilver2/template/timezone.js
@@ -13,7 +13,7 @@ $(document).ready(
 );
 
 $(document).ready(
-	phpbb.timezonePreselectSelect($('#tz_select_date_suggest').attr('data-is-registration') == 'true')
+	phpbb.timezonePreselectSelect($('#tz_select_date_suggest').attr('timezone-preselect') == 'true')
 );
 
 })(jQuery); // Avoid conflicts with other libraries
diff --git a/phpBB/styles/subsilver2/template/timezone_option.html b/phpBB/styles/subsilver2/template/timezone_option.html
index 71c5cf8a30..26ba2388c9 100644
--- a/phpBB/styles/subsilver2/template/timezone_option.html
+++ b/phpBB/styles/subsilver2/template/timezone_option.html
@@ -7,7 +7,7 @@
 				<option value="">{L_SELECT_CURRENT_TIME}</option>
 				{S_TZ_DATE_OPTIONS}
 			</select><br />
-			<input type="button" id="tz_select_date_suggest" class="btnlite" style="display: none;" data-is-registration="<!-- IF S_TZ_PRESELECT -->true<!-- ELSE -->false<!-- ENDIF -->" data-l-suggestion="{L_TIMEZONE_DATE_SUGGESTION}" value="{L_TIMEZONE_DATE_SUGGESTION}" />
+			<input type="button" id="tz_select_date_suggest" class="btnlite" style="display: none;" timezone-preselect="<!-- IF S_TZ_PRESELECT -->true<!-- ELSE -->false<!-- ENDIF -->" data-l-suggestion="{L_TIMEZONE_DATE_SUGGESTION}" value="{L_TIMEZONE_DATE_SUGGESTION}" />
 		</div>
 		<!-- ENDIF -->
 		<select name="tz" id="timezone" class="autowidth tz_select">