diff --git a/src/corelib/time/qtimezone.cpp b/src/corelib/time/qtimezone.cpp
index c593af544f0..9839107e80a 100644
--- a/src/corelib/time/qtimezone.cpp
+++ b/src/corelib/time/qtimezone.cpp
@@ -1504,9 +1504,13 @@ QList<QByteArray> QTimeZone::availableTimeZoneIds(QLocale::Territory territory)
     Returns a list of all available IANA time zone IDs with a given standard
     time offset of \a offsetSeconds.
 
+    Where the given offset is supported, \c{QTimeZone(offsetSeconds).id()} is
+    included in the list, even if it is not an IANA ID. This only arises when
+    there is no IANA UTC-offset ID with the given offset.
+
     This method is only available when feature \c timezone is enabled.
 
-    \sa isTimeZoneIdAvailable()
+    \sa isTimeZoneIdAvailable(), QTimeZone(int)
 */
 
 QList<QByteArray> QTimeZone::availableTimeZoneIds(int offsetSeconds)
diff --git a/src/corelib/time/qtimezoneprivate.cpp b/src/corelib/time/qtimezoneprivate.cpp
index 97f2f85e52a..71b1674b846 100644
--- a/src/corelib/time/qtimezoneprivate.cpp
+++ b/src/corelib/time/qtimezoneprivate.cpp
@@ -989,6 +989,12 @@ QList<QByteArray> QUtcTimeZonePrivate::availableTimeZoneIds(qint32 offsetSeconds
         }
         result << id.toByteArray();
     }
+    // CLDR only has round multiples of a quarter hour, and only some of
+    // those. For anything else, throw in the ID we would use for this offset
+    // (if we'd accept that ID).
+    QByteArray isoName = isoOffsetFormat(offsetSeconds, QTimeZone::ShortName).toUtf8();
+    if (offsetFromUtcString(isoName) == qint64(offsetSeconds) && !result.contains(isoName))
+        result << isoName;
     // Not guaranteed to be sorted, so sort:
     std::sort(result.begin(), result.end());
     // ### assuming no duplicates