diff --git a/bin/build b/bin/build
index 1f0ecac..b7bb7d9 100755
--- a/bin/build
+++ b/bin/build
@@ -133,23 +133,9 @@ if 1: # has MPW
 
 # Tell MPW what to do when it starts (can use {Src} in their -c command)
 if config.passthru:
-    bootscript = '''
-        Set Src Disk:Src:
-        Export Src
-        Directory {Src}
-        Set Exit 0
-
-        ''' + config.passthru + '''
-
-        # DumpObj SeriousFile.c.o to SeriousFile.c.d
-        Files -r -o -f -t 'OBJ ' -c 'MPS ' Disk:Src:BuildResults | StreamEdit ∂
-            -e "1,$ change 'If ∂`Newer ' . ' ' . '.dump∂`; DumpObj ' . '>' . '.dump; End'; replace -c 2 /[a-z]+.dump/ 'd'" ∂
-            >Disk:DumpObjScript
-        Disk:DumpObjScript
-
-        Quit
-    '''
-    vol['MPW']['UserStartup'].data = bootscript.replace('\n', '\r').encode('mac_roman')
+    bootscript = 'Set Src Disk:Src:; Export Src; Directory {Src}\r'
+    bootscript += 'Set Exit 0; %s; Quit\r' % config.passthru
+    vol['MPW']['UserStartup'].data = bootscript.encode('mac_roman')
 
 # Evil tuning: more RAM for MPW because some tools do not use temp mem
 mpw = list(macresources.parse_file(vol['MPW']['MPW Shell'].rsrc))