diff --git a/debian/rules b/debian/rules
index 9eeebc0..a28aa19 100755
--- a/debian/rules
+++ b/debian/rules
@@ -2,7 +2,8 @@
 
 derives_from_ubuntu := $(shell (dpkg-vendor --derives-from Ubuntu && echo "yes") || echo "no")
 
-CFLAGS=-DLANG_EN -O2 -Wall
+CFLAGS = $(shell dpkg-buildflags --get CFLAGS)
+CFLAGS += -DLANG_ENG -Wall
 
 %:
 	dh $@ --parallel --builddirectory=build/