diff --git a/Win/PmCleanSystem.icl b/Win/PmCleanSystem.icl
index 7775e2b984c3fff2bf1fd6a26250f873e452e2f1..6545ea731a4b918a5f2516e517182de5ab703cc8 100644
--- a/Win/PmCleanSystem.icl
+++ b/Win/PmCleanSystem.icl
@@ -899,7 +899,8 @@ compile_with_cache2 path directory arguments compiler_thread_id compiler_thread_
 RunExternalCommand :: !String ![String] !String !*GeneralSt -> *(!Int, ![String], !*GeneralSt)
 RunExternalCommand cmd args startupdir ps
 	# command = foldl (\cmd arg -> cmd +++ " " +++ arg) cmd [quoted_string arg \\ arg <- args]
-	  dir = RemoveFilename cmd
+	| size command >= 32768 = (-1,["Error: command line is too long (consider moving the project to a location closer to the filesystem root): " +++ command % (0,200) +++ "..."],ps)
+	# dir = RemoveFilename cmd
 	  errorsfilename = tooltempdir +++ DirSeparatorString +++ "errors"
 	  (didit,exit_code,_) = call_process_with_directory_and_redirected_std_error command dir errorsfilename 99
 	| not didit = abort ("Could not run external command '" +++ command +++ "'\n")