--- a/camb/constants.f90
+++ b/camb/constants.f90
@@ -87,7 +87,7 @@
         global_error_message=''
     end if
     if (present(id)) then
-        if (id==0) error stop('Error id must be non-zero')
+        if (id==0) error stop
         global_error_flag=id
     else
         global_error_flag=-1
