How to fail on a find with grep using make?

[Gary Turner]

Hi,
Apologies (and please let me know) if this is an inappropriate question for 
this list.
I'm using grep to compile files created by a gui editor. Occasionally a 'bad 
thing' gets into the files, and I'd like the compile to fail if that 'bad 
thing' is found in the file. By default grep 'fails' on not found, which 
would normally stop make.
What I want is something like  error if not grep 'bad thing' $<
I'm using cmd.exe.
I had a look at shell, then if, but it didn't seem to work. Is it possible 
it wasn't waiting for the command to finish before doing the if statement?
I wasn't sure if it was possible to use the $< variable with shell either.