diff --git a/Plugin/Crack.cpp b/Plugin/Crack.cpp
index ebba4fe87a72765e280d53b426b06a4ae1cd3fb9..a8d76a4b62056918d890a7a2f2d365b5fa816979 100644
--- a/Plugin/Crack.cpp
+++ b/Plugin/Crack.cpp
@@ -34,11 +34,12 @@ extern "C"
 std::string GMSH_CrackPlugin::getHelp() const
 {
   return "Plugin(Crack) creates a crack around the physical "
-    "group `PhysicalGroup' of dimension `Dimension' (1 or 2). "
+    "group `PhysicalGroup' of dimension `Dimension' (1 or 2), "
+    "embedded in a mesh of dimension `Dimension' + 1. "
     "The plugin duplicates the vertices and the elements on "
     "the crack and stores them in a new discrete curve "
     "(`Dimension' = 1) or surface (`Dimension' = 2). The "
-    "elements touching the crack on the negative side "
+    "elements touching the crack on the ``negative'' side "
     "are modified to use the newly generated vertices."
     "If `OpenBoundaryPhysicalGroup' is given (> 0), its "
     "vertices are duplicated and the crack will be left "