diff --git a/pycallgraph/output/output.py b/pycallgraph/output/output.py
index 662d563..57de41d 100644
--- a/pycallgraph/output/output.py
+++ b/pycallgraph/output/output.py
@@ -90,6 +90,9 @@ def done(self):
         raise NotImplementedError('done')
 
     def ensure_binary(self, cmd):
+        if os.path.isfile(cmd) and os.access(cmd, os.X_OK):
+            return
+
         if find_executable(cmd):
             return