diff --git a/chem_proc/src/cam_chempp/mozpp.main.f b/chem_proc/src/cam_chempp/mozpp.main.f
index f9a2e4c649..9a2e208035 100644
--- a/chem_proc/src/cam_chempp/mozpp.main.f
+++ b/chem_proc/src/cam_chempp/mozpp.main.f
@@ -71,7 +71,7 @@ program mozart_pp
       character(len=580) :: command, cpp_command
       character(len=256) :: errcom, filout, filin
       character(len=64)  :: oper_flpth
-      character(len=64)  :: cpp_dir, cpp_opts
+      character(len=256)  :: cpp_dir, cpp_opts
       character(len=64)  :: wrk_dir
       character(len=64)  :: tar_flnm
       character(len=64)  :: subfile