diff --git a/Code/Mantid/MantidQt/SliceViewer/src/LineOverlay.cpp b/Code/Mantid/MantidQt/SliceViewer/src/LineOverlay.cpp
index d6c316a4be02..dd3f765dd991 100644
--- a/Code/Mantid/MantidQt/SliceViewer/src/LineOverlay.cpp
+++ b/Code/Mantid/MantidQt/SliceViewer/src/LineOverlay.cpp
@@ -387,10 +387,21 @@ namespace SliceViewer
     double distance = fabs( diff.x()*(current.y()-pixA.y()) - (current.x() - pixA.x())*diff.y() )
         / sqrt(diff.x()*diff.x() + diff.y()*diff.y());
 
-    // Margin of 6 pixels, and must be between the 2 limits
-    return ((distance < 7) &&
-        isBetween( current.x(), pixA.x(), pixB.x()) &&
-        isBetween( current.y(), pixA.y(), pixB.y()) );
+    // Margin of 6 pixels, and must be between the 2 limits (if the limits are not the same)
+    bool retval = false;
+    if (distance < 7)
+    {
+      retval = true;
+      if ((pixA.x() != pixB.x()) && (!isBetween( current.x(), pixA.x(), pixB.x())))
+      {
+        retval = false;
+      }
+      if ((pixA.y() != pixB.y()) && (!isBetween( current.y(), pixA.y(), pixB.y())))
+      {
+        retval = false;
+      }
+    }
+    return retval;
   }
 
   //-----------------------------------------------------------------------------------------------