diff --git a/tests/datetime/datetimetest.cpp b/tests/datetime/datetimetest.cpp
index c1f156038d..12c28f12e6 100644
--- a/tests/datetime/datetimetest.cpp
+++ b/tests/datetime/datetimetest.cpp
@@ -21,6 +21,7 @@
 #endif // WX_PRECOMP
 
 #include "wx/wxcrt.h"       // for wxStrstr()
+#include "wx/scopeguard.h"
 
 #include "wx/private/localeset.h"
 
@@ -2538,6 +2539,12 @@ TEST_CASE("Easter", "[datetime][holiday][easter]")
 
 TEST_CASE("US Catholic Holidays", "[datetime][holiday]")
 {
+    // Clear the wxDateTimeWorkDays that exists by default, and restore it at the end,
+    // after cleaning up the authority tested here.
+    wxDateTimeHolidayAuthority::ClearAllAuthorities();
+    wxON_BLOCK_EXIT0(wxDateTimeHolidayAuthority::ClearAllAuthorities);
+    wxON_BLOCK_EXIT1(wxDateTimeHolidayAuthority::AddAuthority, new wxDateTimeWorkDays);
+
     SECTION("Ascension")
     {
         wxDateTime ascension = wxDateTimeUSCatholicFeasts::GetThursdayAscension(2023);
@@ -2565,6 +2572,12 @@ TEST_CASE("US Catholic Holidays", "[datetime][holiday]")
 
 TEST_CASE("Christian Holidays", "[datetime][holiday][christian]")
 {
+    // Clear the wxDateTimeWorkDays that exists by default, and restore it at the end,
+    // after cleaning up the authority tested here.
+    wxDateTimeHolidayAuthority::ClearAllAuthorities();
+    wxON_BLOCK_EXIT0(wxDateTimeHolidayAuthority::ClearAllAuthorities);
+    wxON_BLOCK_EXIT1(wxDateTimeHolidayAuthority::AddAuthority, new wxDateTimeWorkDays);
+
     SECTION("Easter")
     {
         wxDateTime easter = wxDateTimeChristianHolidays::GetEaster(2023);