diff --git a/cuckoo/core/extract.py b/cuckoo/core/extract.py
index 074227ef8..3f2860307 100644
--- a/cuckoo/core/extract.py
+++ b/cuckoo/core/extract.py
@@ -52,7 +52,7 @@ class ExtractManager(object):
                 ext.yara_rules = ext.yara_rules,
 
     def __del__(self):
-        ExtractManager._instances.pop(self.task_id, None)
+        self._instances.pop(self.task_id, None)
 
     def write_extracted(self, ext, payload):
         dirpath = cwd("extracted", analysis=self.task_id)
diff --git a/cuckoo/misc.py b/cuckoo/misc.py
index 78151ed75..aa9f94644 100644
--- a/cuckoo/misc.py
+++ b/cuckoo/misc.py
@@ -119,6 +119,7 @@ def load_signatures():
     # Forward everything from lib.cuckoo to "our" cuckoo module.
     sys.modules["lib"] = types.ModuleType("lib")
     sys.modules["lib.cuckoo"] = sys.modules["cuckoo"]
+    sys.modules["lib.cuckoo.common"] = sys.modules["cuckoo.common"]
 
     # Import this here in order to avoid recursive import statements.
     from cuckoo.common.abstracts import Signature
@@ -133,7 +134,7 @@ def load_signatures():
     dont_write_bytecode = sys.dont_write_bytecode
     sys.dont_write_bytecode = True
 
-    # Trigger an import on $CWD/signatures. This will automatically import
+    # Trigger an import on $CWD/signatures/. This will automatically import
     # recursively down the various directories through the use of
     # enumerate_plugins(), which the Cuckoo Community adheres to. For this to
     # work we temporarily insert the CWD in Python's path.