diff --git a/src/Extrema/Extrema_ExtCC.cxx b/src/Extrema/Extrema_ExtCC.cxx
index def27cbe5e..0466dc2ec1 100644
--- a/src/Extrema/Extrema_ExtCC.cxx
+++ b/src/Extrema/Extrema_ExtCC.cxx
@@ -411,7 +411,7 @@ void Extrema_ExtCC::PrepareParallelResult(const Standard_Real theUt11,
   if (((aType1 != GeomAbs_Line) && (aType1 != GeomAbs_Circle)) ||
       ((aType2 != GeomAbs_Line) && (aType2 != GeomAbs_Circle)))
   {
-    mySqDist.Append(theSqDist);
+    //mySqDist.Append(theSqDist);
     myDone = Standard_True;
     myIsParallel = Standard_True;
     return;
@@ -432,11 +432,7 @@ void Extrema_ExtCC::PrepareParallelResult(const Standard_Real theUt11,
                                   !isReversed ? theUt21 : theUt11,
                                   !isReversed ? theUt22 : theUt12);
 
-    if (ExtPLin.IsDone())
-    {
-      mySqDist.Append(theSqDist);
-    }
-    else
+    if (!ExtPLin.IsDone())
     {
       myIsParallel = Standard_False;
     }
@@ -837,7 +833,9 @@ void Extrema_ExtCC::PrepareResults(const Extrema_ExtElC&  AlgExt,
     if (myIsParallel) {
       PrepareParallelResult(Ut11, Ut12, Ut21, Ut22, AlgExt.SquareDistance());
     }
-    else {
+
+    if(mypoints.IsEmpty())
+    {
       NbExt = AlgExt.NbExt();
       for (i = 1; i <= NbExt; i++) {
 	// Verification de la validite des parametres
@@ -911,7 +909,7 @@ void Extrema_ExtCC::PrepareResults(const Extrema_ECC&   AlgExt,
     {
       PrepareParallelResult(Ut11, Ut12, Ut21, Ut22, AlgExt.SquareDistance());
     }
-    else
+    if(mypoints.IsEmpty())
     {
       NbExt = AlgExt.NbExt();
       for (i = 1; i <= NbExt; i++)
diff --git a/tests/bugs/modalg_7/bug24909_4 b/tests/bugs/modalg_7/bug24909_4
new file mode 100644
index 0000000000..d2fc6cc878
--- /dev/null
+++ b/tests/bugs/modalg_7/bug24909_4
@@ -0,0 +1,15 @@
+puts "========"
+puts "0024909: Modeling Algorithms - SIGSEGV in buildsweep"
+puts "========"
+puts ""
+
+pload ALL
+circle c1 0 0 0 40
+mkedge e1 c1
+wire w1 e1
+line l1 0 0 0 0 0 20
+mkedge e2 l1 0 10
+wire w2 e2
+mksweep w1
+addsweep w2
+buildsweep sw1