diff --git a/lib/controller/controller.py b/lib/controller/controller.py
index 3c8726e22..7afb4c89b 100644
--- a/lib/controller/controller.py
+++ b/lib/controller/controller.py
@@ -209,9 +209,8 @@ def _saveToHashDB():
             _[key].data.update(injection.data)
     hashDBWrite(HASHDB_KEYS.KB_INJECTIONS, _.values(), True)
 
-    _ = hashDBRetrieve(HASHDB_KEYS.KB_ABS_FILE_PATHS, True) or set()
-    _.update(kb.absFilePaths)
-    hashDBWrite(HASHDB_KEYS.KB_ABS_FILE_PATHS, _, True)
+    _ = hashDBRetrieve(HASHDB_KEYS.KB_ABS_FILE_PATHS, True)
+    hashDBWrite(HASHDB_KEYS.KB_ABS_FILE_PATHS, kb.absFilePaths | (_ if isinstance(_, set) else set()), True)
 
     if not hashDBRetrieve(HASHDB_KEYS.KB_CHARS):
         hashDBWrite(HASHDB_KEYS.KB_CHARS, kb.chars, True)
diff --git a/lib/utils/hashdb.py b/lib/utils/hashdb.py
index 44c1987fb..10e85afaf 100644
--- a/lib/utils/hashdb.py
+++ b/lib/utils/hashdb.py
@@ -97,6 +97,7 @@ class HashDB(object):
             try:
                 retVal = unserializeObject(retVal)
             except:
+                retVal = None
                 warnMsg = "error occurred while unserializing value for session key '%s'. " % key
                 warnMsg += "If the problem persists please rerun with `--flush-session`"
                 logger.warn(warnMsg)