diff --git a/README.md b/README.md
index 821ccc5..8d13121 100644
--- a/README.md
+++ b/README.md
@@ -227,6 +227,16 @@ This command remeshes the atoms/elements within the group to the new element siz
 
 If this option is passed then all files are automatically overwritten without asking the user.
 
+### Option boundary
+
+``` 
+-boundary box_bc
+```
+
+This allows the user to specify the boundary conditions for the model being outputted. The format is a 3 character string with `p` indicating periodic and `s` indicating shrink-wrapped.
+
+**Example:** `-boundary psp`
+
 ## Position Specification
 
 Specifying positions in cacmb can be done through a variety of ways. Examples of each format is shown below.
diff --git a/src/call_option.f90 b/src/call_option.f90
index f750ca6..0d7f9c7 100644
--- a/src/call_option.f90
+++ b/src/call_option.f90
@@ -2,6 +2,7 @@ subroutine call_option(option, arg_pos)
     use parameters
     use opt_disl
     use opt_group
+    use box
     implicit none
 
     integer, intent(inout) :: arg_pos
@@ -18,6 +19,11 @@ subroutine call_option(option, arg_pos)
     case('-wrap')
         arg_pos = arg_pos + 1
         continue
+    case('-boundary')
+        arg_pos=arg_pos+1
+        call get_command_argument(arg_pos, box_bc)
+        print *, box_bc
+        arg_pos=arg_pos+1
     case default
         print *, 'Option ', trim(adjustl(option)), ' is not currently accepted.'
         stop 3