diff --git a/modules/gui/src/tools/measure_tool.cc b/modules/gui/src/tools/measure_tool.cc
index 79de57b9689ca180c61b9e81a13034f2444394c2..5b4cc3d2cd039fb59cbf3bbe0bc6326bb2a8e2e6 100644
--- a/modules/gui/src/tools/measure_tool.cc
+++ b/modules/gui/src/tools/measure_tool.cc
@@ -205,7 +205,7 @@ Measurement::Measurement(mol::AtomHandleList ahl, gfx::Color col, Real line_widt
       name_=ahl_[0].GetQualifiedName()+" - "+ahl_[1].GetQualifiedName()+" - "
              +ahl_[2].GetQualifiedName();
       measurement_=57.2958*geom::Angle(ahl_[0].GetPos()-ahl_[1].GetPos(),
-                                       ahl_[1].GetPos()-ahl_[2].GetPos());
+                                       ahl_[2].GetPos()-ahl_[1].GetPos());
       valid_=true;
       break;
     }