diff --git a/ccpp/data/GFS_typedefs.F90 b/ccpp/data/GFS_typedefs.F90
index 7aaaac08c..0221ee37d 100644
--- a/ccpp/data/GFS_typedefs.F90
+++ b/ccpp/data/GFS_typedefs.F90
@@ -4438,7 +4438,7 @@ subroutine control_initialize (Model, nlunit, fn_nml, me, master, &
            endif
 
            ! More specific chemical tracer names:
-           call label_dtend_tracer(Model,100+Model%ntchs,'so2','sulfur dioxide concentration')
+           call label_dtend_tracer(Model,100+Model%ntchs,'so2','sulfur dioxide concentration','kg kg-1 s-1')
            if(Model%ntchm>0) then
               ! Need better descriptions of these.
               call label_dtend_tracer(Model,100+Model%ntchm+Model%ntchs-1,'pp10','pp10 concentration','kg kg-1 s-1')