diff --git a/tools/perf.py b/tools/perf.py
index 8301201d7..cf7202248 100755
--- a/tools/perf.py
+++ b/tools/perf.py
@@ -31,8 +31,8 @@ class PerfTest(object):
         args.append(self.rom)
         env = {}
         if 'LD_LIBRARY_PATH' in os.environ:
-            env['LD_LIBRARY_PATH'] = os.environ['LD_LIBRARY_PATH']
-            env['DYLD_LIBRARY_PATH'] = os.environ['LD_LIBRARY_PATH'] # Fake it on OS X
+            env['LD_LIBRARY_PATH'] = os.path.abspath(os.environ['LD_LIBRARY_PATH'])
+            env['DYLD_LIBRARY_PATH'] = env['LD_LIBRARY_PATH'] # Fake it on OS X
         proc = subprocess.Popen(args, stdout=subprocess.PIPE, cwd=cwd, universal_newlines=True, env=env)
         try:
             self.wait(proc)