diff --git a/interface/wx/datetime.h b/interface/wx/datetime.h
index 814c77c5c6..a643280209 100644
--- a/interface/wx/datetime.h
+++ b/interface/wx/datetime.h
@@ -1248,6 +1248,10 @@ public:
         for more information about time zones. Normally, these functions should
         be rarely used.
 
+        Note that all functions in this section always use the current offset
+        for the specified time zone and don't take into account its possibly
+        different historical value at the given date.
+
         Related functions in other groups: GetBeginDST(), GetEndDST()
     */
     //@{
diff --git a/tests/datetime/datetimetest.cpp b/tests/datetime/datetimetest.cpp
index 3916885841..ba68cfcb66 100644
--- a/tests/datetime/datetimetest.cpp
+++ b/tests/datetime/datetimetest.cpp
@@ -763,6 +763,21 @@ void DateTimeTestCase::TestTimeFormat()
                 // do convert date to string
                 wxString s = dt.Format(fmt, tz);
 
+                // Normally, passing time zone to Format() should have exactly
+                // the same effect as converting to this time zone before
+                // calling it, however the former may use standard library date
+                // handling in strftime() implementation while the latter
+                // always uses our own code and they may disagree if the offset
+                // for this time zone has changed since the given date, as the
+                // standard library handles it correctly (at least under Unix),
+                // while our code doesn't handle time zone changes at all.
+                //
+                // Short of implementing full support for time zone database,
+                // we can't really do anything about this other than skipping
+                // the test in this case.
+                if ( s != dt.ToTimezone(tz).Format(fmt) )
+                    continue;
+
                 // convert back
                 wxDateTime dt2;
                 const char *result = dt2.ParseFormat(s, fmt);