diff --git a/android-interact.sh b/android-interact.sh
index ba2d890..3b2ed33 100755
--- a/android-interact.sh
+++ b/android-interact.sh
@@ -2,7 +2,10 @@
 # File: android-interact.sh
 # Date: Sun Jan 11 23:05:58 2015 +0800
 # Author: Yuxin Wu <ppwwyyxxc@gmail.com>
-PROG_NAME=`readlink -f "$0"`
+
+source compatibility.sh
+
+PROG_NAME=`$REALPATH "$0"`
 PROG_DIR=`dirname "$PROG_NAME"`
 cd "$PROG_DIR"
 
@@ -15,7 +18,7 @@ adb root
 
 if [[ $1 == "uin" ]]; then
 	adb pull $MM_DIR/shared_prefs/system_config_prefs.xml 2>/dev/null
-	uin=$(grep 'default_uin' system_config_prefs.xml | grep -o 'value="[0-9]*' | cut -c 8-)
+	uin=$(grep 'default_uin' system_config_prefs.xml | $GREP -o 'value="[0-9]*' | cut -c 8-)
 	[[ -n $uin ]] || {
 		echo "Failed to get wechat uin. You can try other methods, or report a bug."
 		exit 1
@@ -23,7 +26,7 @@ if [[ $1 == "uin" ]]; then
 	rm system_config_prefs.xml
 	echo "Got wechat uin: $uin"
 elif [[ $1 == "imei" ]]; then
-	imei=$(adb shell dumpsys iphonesubinfo | grep 'Device ID' | grep -o '[0-9]*')
+	imei=$(adb shell dumpsys iphonesubinfo | grep 'Device ID' | $GREP -o '[0-9]+')
 	[[ -n $imei ]] || {
 		echo "Failed to get imei. You can try other methods, or report a bug."
 		exit 1
diff --git a/compatibility.sh b/compatibility.sh
new file mode 100755
index 0000000..cf1688a
--- /dev/null
+++ b/compatibility.sh
@@ -0,0 +1,20 @@
+#!/bin/bash -e
+# $File: compatibility.sh
+# $Date: Mon Jan 19 14:27:25 2015 +0800
+# Author: Vury Leo <i[at]vuryleo[dot]com>
+
+realpath() {
+  [[ $1 = /* ]] && echo "$1" || echo "$PWD/${1#./}"
+}
+
+if [ `uname` = 'Darwin' ]
+then
+  REALPATH='realpath'
+  GREP='grep -E'
+  MD5SUM='md5'
+else
+  REALPATH='readlink -f'
+  GREP='grep'
+  MD5SUM='md5sum'
+fi
+
diff --git a/decrypt_db.sh b/decrypt_db.sh
index 9c882e8..0e22c72 100755
--- a/decrypt_db.sh
+++ b/decrypt_db.sh
@@ -3,6 +3,8 @@
 # Date: Sun Jan 11 22:30:50 2015 +0800
 # Author: Yuxin Wu <ppwwyyxxc@gmail.com>
 
+source compatibility.sh
+
 MSGDB=$1
 imei=$2
 uin=$3
@@ -20,7 +22,7 @@ if [[ -f $output ]]; then
 fi
 
 
-KEY=$(echo -n "$imei$uin" | md5sum | cut -b 1-7)
+KEY=$(echo -n "$imei$uin" | $MD5SUM | cut -b 1-7)
 echo "KEY: $KEY"
 
 uname -m | grep x86_64 > /dev/null || version=32bit && version=64bit