diff --git a/src/core/geometry/qgsgeos.cpp b/src/core/geometry/qgsgeos.cpp
index 869a900b1e6..b90b3116362 100644
--- a/src/core/geometry/qgsgeos.cpp
+++ b/src/core/geometry/qgsgeos.cpp
@@ -2344,7 +2344,7 @@ static geos::unique_ptr _mergeLinestrings( const GEOSGeometry *line1, const GEOS
     return nullptr;
 
   bool intersectionAtOrigLineEndpoint =
-    ( intersectionPoint.x() == x1 && intersectionPoint.y() == y1 ) ||
+    ( intersectionPoint.x() == x1 && intersectionPoint.y() == y1 ) !=
     ( intersectionPoint.x() == x2 && intersectionPoint.y() == y2 );
   bool intersectionAtReshapeLineEndpoint =
     ( intersectionPoint.x() == rx1 && intersectionPoint.y() == ry1 ) ||
diff --git a/tests/src/python/test_qgsgeometry.py b/tests/src/python/test_qgsgeometry.py
index 100c5190b0d..26480a2b054 100644
--- a/tests/src/python/test_qgsgeometry.py
+++ b/tests/src/python/test_qgsgeometry.py
@@ -2334,6 +2334,18 @@ class TestQgsGeometry(unittest.TestCase):
         wkt = g.asWkt()
         assert compareWkt(expWkt, wkt), "testReshape failed: mismatch Expected:\n%s\nGot:\n%s\n" % (expWkt, wkt)
 
+        # Test reshape a polygon with a line starting or ending at the polygon's first vertex, no change expexted
+        g = QgsGeometry.fromWkt('Polygon ((0 0, 1 0, 1 1, 0 1, 0 0))')
+        expWkt = g.asWkt()
+        g.reshapeGeometry(QgsLineString([QgsPoint(0, 0), QgsPoint(-1, -1)]))
+        assert compareWkt(g.asWkt(), expWkt), "testReshape failed: mismatch Expected:\n%s\nGot:\n%s\n" % (expWkt, wkt)
+
+        # Test reshape a polygon with a line starting or ending at the polygon's first vertex
+        g = QgsGeometry.fromWkt('Polygon ((0 0, 1 0, 1 1, 0 1, 0 0))')
+        g.reshapeGeometry(QgsLineString([QgsPoint(0, 0), QgsPoint(0.5, 0.5), QgsPoint(0, 1)]))
+        expWkt = 'Polygon ((0 0, 1 0, 1 1, 0 1, 0.5 0.5, 0 0))'
+        assert compareWkt(g.asWkt(), expWkt), "testReshape failed: mismatch Expected:\n%s\nGot:\n%s\n" % (expWkt, wkt)
+
         # Test reshape a line from first/last vertex
         g = QgsGeometry.fromWkt('LineString (0 0, 5 0, 5 1)')
         # extend start