diff --git a/python/core/auto_generated/geometry/qgscircularstring.sip.in b/python/core/auto_generated/geometry/qgscircularstring.sip.in
index f4f570ddb4e..6a5e94a1dbd 100644
--- a/python/core/auto_generated/geometry/qgscircularstring.sip.in
+++ b/python/core/auto_generated/geometry/qgscircularstring.sip.in
@@ -49,6 +49,9 @@ z and m types accordingly.
 
 This constructor is more efficient then calling :py:func:`~QgsCircularString.setPoints`.
 
+If the sizes of ``x`` and ``y`` are non-equal then the resultant circular string
+will be created using the minimum size of these arrays.
+
 .. warning::
 
    It is the caller's responsibility to ensure that the supplied arrays
diff --git a/python/core/auto_generated/geometry/qgslinestring.sip.in b/python/core/auto_generated/geometry/qgslinestring.sip.in
index f735d3cafe5..ee13fc804ae 100644
--- a/python/core/auto_generated/geometry/qgslinestring.sip.in
+++ b/python/core/auto_generated/geometry/qgslinestring.sip.in
@@ -56,6 +56,9 @@ argument. If ``is25DType`` is ``True`` (and the ``m`` vector is unfilled) then
 the created Linestring will be a LineString25D type. Otherwise, the
 LineString will be LineStringZ (or LineStringZM) type.
 
+If the sizes of ``x`` and ``y`` are non-equal then the resultant linestring
+will be created using the minimum size of these arrays.
+
 .. versionadded:: 3.0
 %End
 
diff --git a/src/core/geometry/qgscircularstring.h b/src/core/geometry/qgscircularstring.h
index 60d575e8b1d..e6cd7533745 100644
--- a/src/core/geometry/qgscircularstring.h
+++ b/src/core/geometry/qgscircularstring.h
@@ -57,6 +57,9 @@ class CORE_EXPORT QgsCircularString: public QgsCurve
      *
      * This constructor is more efficient then calling setPoints().
      *
+     * If the sizes of \a x and \a y are non-equal then the resultant circular string
+     * will be created using the minimum size of these arrays.
+     *
      * \warning It is the caller's responsibility to ensure that the supplied arrays
      * are of odd sizes.
      *
diff --git a/src/core/geometry/qgslinestring.h b/src/core/geometry/qgslinestring.h
index a56dbf47f31..8c9db314459 100644
--- a/src/core/geometry/qgslinestring.h
+++ b/src/core/geometry/qgslinestring.h
@@ -71,6 +71,9 @@ class CORE_EXPORT QgsLineString: public QgsCurve
      * the created Linestring will be a LineString25D type. Otherwise, the
      * LineString will be LineStringZ (or LineStringZM) type.
      *
+     * If the sizes of \a x and \a y are non-equal then the resultant linestring
+     * will be created using the minimum size of these arrays.
+     *
      * \since QGIS 3.0
      */
     QgsLineString( const QVector<double> &x, const QVector<double> &y,