diff --git a/DiffractionGratings/README.txt b/DiffractionGratings/README.txt
index 68eddaafc367d241b7bac6daf3fc7bdad78ba0a2..84f6e14a07ff1165c24ee0d0d8d2878a571313fb 100644
--- a/DiffractionGratings/README.txt
+++ b/DiffractionGratings/README.txt
@@ -9,7 +9,7 @@ Quick start 3D
 --------------
 
 To run the test cases, type in the command line :
-'gmsh grating3D.pro -setstring test_case hole'
+`gmsh grating3D.pro -setstring test_case hole`
 
 Additional info
 ---------------