diff --git a/build.xml b/build.xml
index 7db9217..db98ebb 100644
--- a/build.xml
+++ b/build.xml
@@ -28,6 +28,15 @@
          -->
     <property file="ant.properties" />
 
+    <!-- if sdk.dir was not set from one of the property file, then
+         get it from the ANDROID_HOME env var.
+         This must be done before we load project.properties since
+         the proguard config can use sdk.dir -->
+    <property environment="env" />
+    <condition property="sdk.dir" value="${env.ANDROID_HOME}">
+        <isset property="env.ANDROID_HOME" />
+    </condition>
+
     <!-- The project.properties file is created and updated by the 'android'
          tool, as well as ADT.
 
@@ -41,7 +50,7 @@
 
     <!-- quick check on sdk.dir -->
     <fail
-            message="sdk.dir is missing. Make sure to generate local.properties using 'android update project' or to inject it through an env var"
+            message="sdk.dir is missing. Make sure to generate local.properties using 'android update project' or to inject it through the ANDROID_HOME environment variable."
             unless="sdk.dir"
     />