diff -urN exim-4.60.org/OS/Makefile-Linux exim-4.60/OS/Makefile-Linux
--- exim-4.60.org/OS/Makefile-Linux	2005-11-28 11:57:32.000000000 +0100
+++ exim-4.60/OS/Makefile-Linux	2006-02-17 20:17:00.698452750 +0100
@@ -13,7 +13,7 @@
 CHMOD_COMMAND=look_for_it
 
 # Preserve CFLAGS and CFLAGS_DYNAMIC from the caller/environment
-CFLAGS ?= -O -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
+CFLAGS ?= -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE $(CUSTOM_CFLAGS)
 CFLAGS_DYNAMIC ?= -shared -rdynamic
 
 DBMLIB = -ldb