diff --git a/src/core/geometry/qgscompoundcurve.cpp b/src/core/geometry/qgscompoundcurve.cpp
index 83adc35835c9..7fcc2e1344da 100644
--- a/src/core/geometry/qgscompoundcurve.cpp
+++ b/src/core/geometry/qgscompoundcurve.cpp
@@ -119,11 +119,11 @@ QgsCompoundCurve::QgsCompoundCurve( const QgsCompoundCurve &curve ): QgsCurve( c
   }
 }
 
+// cppcheck-suppress operatorEqVarError
 QgsCompoundCurve &QgsCompoundCurve::operator=( const QgsCompoundCurve &curve )
 {
   if ( &curve != this )
   {
-    clearCache();
     QgsCurve::operator=( curve );
     for ( const QgsCurve *c : curve.mCurves )
     {
diff --git a/tests/src/core/geometry/testqgscompoundcurve.cpp b/tests/src/core/geometry/testqgscompoundcurve.cpp
index 25f44dcb69db..72184bf75d5f 100644
--- a/tests/src/core/geometry/testqgscompoundcurve.cpp
+++ b/tests/src/core/geometry/testqgscompoundcurve.cpp
@@ -619,6 +619,13 @@ void TestQgsCompoundCurve::assignment()
 
   QVERIFY( cc1 != cc2 );
 
+  QgsLineString ls2;
+  ls2.setPoints( QgsPointSequence() << QgsPoint( Qgis::WkbType::PointM, 3, 4, 5, 6 )
+                 << QgsPoint( Qgis::WkbType::PointM, 1 / 2.0, 5 / 7.0, 1, 3 )
+                 << QgsPoint( Qgis::WkbType::PointM, 2, 3, 5, 7 ) );
+  cc2.addCurve( ls2.clone() );
+  QVERIFY( cc1 != cc2 );
+
   cc2 = cc1;
   QCOMPARE( cc1, cc2 );
 }