diff --git a/tests/build_docker_image.py b/tests/build_docker_image.py
index 0a020629..c64c985a 100755
--- a/tests/build_docker_image.py
+++ b/tests/build_docker_image.py
@@ -49,7 +49,7 @@ def sh(s, *args):
     return shlex.split(s)
 
 
-mydir = os.path.dirname(__file__)
+mydir = os.path.abspath(os.path.dirname(__file__))
 with tempfile.NamedTemporaryFile(dir=mydir) as dockerfile_fp:
     dockerfile_fp.write(DOCKERFILE)
     dockerfile_fp.flush()