diff --git a/src/lipase/imageengine.py b/src/lipase/imageengine.py
index 49fee0f..f4990a6 100644
--- a/src/lipase/imageengine.py
+++ b/src/lipase/imageengine.py
@@ -349,6 +349,8 @@ class NullDebugger(IImageProcessingDebugger):
         pass  # do nothing
 
 def mkdir_p(path):
+    if os.path.isdir(path) :
+        return
     try:
         os.makedirs(path)
     except OSError as exc:  # Python >= 2.5