diff --git a/aos/build/build.py b/aos/build/build.py
index 14f890a..f8d2a16 100755
--- a/aos/build/build.py
+++ b/aos/build/build.py
@@ -150,7 +150,7 @@
     with open(FILENAME, 'w') as f:
       f.write('10.9.71')
   with open(FILENAME, 'r') as f:
-    base = f.readline()
+    base = f.readline().strip()
   if device == 'prime':
     return base + '.179'
   elif device == 'robot':