Allow starting from non-root directory
diff --git a/tools/run_tests/run_tests.py b/tools/run_tests/run_tests.py
index 4e0ff85..372321c 100755
--- a/tools/run_tests/run_tests.py
+++ b/tools/run_tests/run_tests.py
@@ -44,6 +44,10 @@
 import watch_dirs
 
 
+ROOT = os.path.abspath(os.path.join(os.path.dirname(sys.argv[0]), '../..'))
+os.chdir(ROOT)
+
+
 # SimpleConfig: just compile with CONFIG=config, and run the binary to test
 class SimpleConfig(object):