diff --git a/README.md b/README.md
index b42b7715187e038f8aaa2005c820ed7ff437c319..2cbefb16a0aca280cc783fb6594b8bd183c0eb78 100644
--- a/README.md
+++ b/README.md
@@ -62,7 +62,7 @@ pycgtool <topology file> <trajectory file> -m <MAP file> -b <BND file>
 
 To use PyCGTOOL to convert a set of atomistic simulation coordinates to CG coordinates:
 ```
-pycgtool <topology file> -m <trajectory file>
+pycgtool <topology file> -m <MAP file>
 ```
 
 Or to convert a complete simulation trajectory: