diff --git a/c_src/Makefile b/c_src/Makefile
index 71d017f..101f570 100644
--- a/c_src/Makefile
+++ b/c_src/Makefile
@@ -1,11 +1,11 @@
-LEVELDB_VSN ?= "nhse-develop-3.0"
-SNAPPY_VSN ?= "1.1.9"
+export LEVELDB_VSN ?= "nhse-develop-3.0"
+export SNAPPY_VSN ?= "1.1.9"
 BASEDIR = $(shell pwd)
 
-LDFLAGS := $(LDFLAGS) -L$(BASEDIR)/system/lib
-LD_LIBRARY_PATH := $(BASEDIR)/system/lib:$(LD_LIBRARY_PATH)
-CFLAGS := $(CFLAGS) -I $(BASEDIR)/system/include -I. -I $(BASEDIR)/leveldb/include -fPIC
-CXXFLAGS := $(CXXFLAGS) -I $(BASEDIR)/system/include -I. -I $(BASEDIR)/leveldb/include -fPIC
+export LDFLAGS := $(LDFLAGS) -L$(BASEDIR)/system/lib
+export LD_LIBRARY_PATH := $(BASEDIR)/system/lib:$(LD_LIBRARY_PATH)
+export CFLAGS := $(CFLAGS) -I $(BASEDIR)/system/include -I. -I $(BASEDIR)/leveldb/include -fPIC
+export CXXFLAGS := $(CXXFLAGS) -I $(BASEDIR)/system/include -I. -I $(BASEDIR)/leveldb/include -fPIC
 
 get-deps:
 	if [ ! -r snappy-$(SNAPPY_VSN).tar.gz ]; then \