diff --git a/libsrc/stlgeom/stlgeom.cpp b/libsrc/stlgeom/stlgeom.cpp
index bdff6cb5..48f64c55 100644
--- a/libsrc/stlgeom/stlgeom.cpp
+++ b/libsrc/stlgeom/stlgeom.cpp
@@ -2139,11 +2139,11 @@ int STLGeometry :: CheckGeometryOverlapping()
 
 
   {
-    Array<int> inters;
     mutex inters_mutex;
     
     ParallelFor( 1, GetNT()+1, [&] (int first, int next)
     {
+      Array<int> inters;
       for (int i=first; i<next; i++) {
 	const STLTriangle & tri = GetTriangle(i);