diff --git a/gns3server/modules/__init__.py b/gns3server/modules/__init__.py
index 5ff0caac..59304d19 100644
--- a/gns3server/modules/__init__.py
+++ b/gns3server/modules/__init__.py
@@ -18,10 +18,10 @@
 import sys
 from .base import IModule
 from .dynamips import Dynamips
-from .iou import IOU
 
 MODULES = [Dynamips]
 
 if sys.platform.startswith("linux"):
     # IOU runs only on Linux
+    from .iou import IOU
     MODULES.append(IOU)
diff --git a/gns3server/modules/dynamips/__init__.py b/gns3server/modules/dynamips/__init__.py
index a3ba093b..34c4a6f0 100644
--- a/gns3server/modules/dynamips/__init__.py
+++ b/gns3server/modules/dynamips/__init__.py
@@ -19,6 +19,7 @@
 Dynamips server module.
 """
 
+import sys
 import os
 import base64
 import tempfile
@@ -116,8 +117,10 @@ class Dynamips(IModule):
         self._dynamips = ""
         self._default_host = "0.0.0.0"
 
-        self._callback = self.add_periodic_callback(self._check_hypervisors, 5000)
-        self._callback.start()
+        if not sys.platform.startswith("win32"):
+            #FIXME: pickle issues Windows
+            self._callback = self.add_periodic_callback(self._check_hypervisors, 5000)
+            self._callback.start()
 
     def stop(self):
         """