diff --git a/plugins/dbms/mssqlserver/enumeration.py b/plugins/dbms/mssqlserver/enumeration.py
index 971f80d45..4bcd49414 100644
--- a/plugins/dbms/mssqlserver/enumeration.py
+++ b/plugins/dbms/mssqlserver/enumeration.py
@@ -11,6 +11,7 @@ from lib.core.agent import agent
 from lib.core.common import arrayizeValue
 from lib.core.common import Backend
 from lib.core.common import getRange
+from lib.core.common import isNoneValue
 from lib.core.common import isNumPosStrValue
 from lib.core.common import isTechniqueAvailable
 from lib.core.common import safeSQLIdentificatorNaming
@@ -93,7 +94,7 @@ class Enumeration(GenericEnumeration):
                 query = rootQuery.inband.query % db
                 value = inject.getValue(query, blind=False)
 
-                if value:
+                if not isNoneValue(value):
                     kb.data.cachedTables[db] = arrayizeValue(value)
 
         if not kb.data.cachedTables and not conf.direct:
@@ -186,7 +187,7 @@ class Enumeration(GenericEnumeration):
                     query += tblQuery
                     values = inject.getValue(query, blind=False)
 
-                    if values:
+                    if not isNoneValue(values):
                         if isinstance(values, basestring):
                             values = [ values ]
 
@@ -279,7 +280,7 @@ class Enumeration(GenericEnumeration):
                     query += " AND %s" % colQuery.replace("[DB]", db)
                     values = inject.getValue(query, blind=False)
 
-                    if values:
+                    if not isNoneValue(values):
                         if isinstance(values, basestring):
                             values = [ values ]
 
diff --git a/plugins/dbms/oracle/enumeration.py b/plugins/dbms/oracle/enumeration.py
index 032225e49..8cc0fe412 100644
--- a/plugins/dbms/oracle/enumeration.py
+++ b/plugins/dbms/oracle/enumeration.py
@@ -10,6 +10,7 @@ See the file 'doc/COPYING' for copying permission
 from lib.core.agent import agent
 from lib.core.common import Backend
 from lib.core.common import getRange
+from lib.core.common import isNoneValue
 from lib.core.common import isNumPosStrValue
 from lib.core.common import isTechniqueAvailable
 from lib.core.common import safeSQLIdentificatorNaming
@@ -64,7 +65,7 @@ class Enumeration(GenericEnumeration):
 
                 return self.getRoles(query2=True)
 
-            if values:
+            if not isNoneValue(values):
                 for value in values:
                     user = None
                     roles = set()
@@ -204,7 +205,7 @@ class Enumeration(GenericEnumeration):
                     query += colQuery
                     values = inject.getValue(query, blind=False)
 
-                    if values:
+                    if not isNoneValue(values):
                         if isinstance(values, basestring):
                             values = [ values ]
 
diff --git a/plugins/generic/enumeration.py b/plugins/generic/enumeration.py
index ea73cf2d1..e410b58e1 100644
--- a/plugins/generic/enumeration.py
+++ b/plugins/generic/enumeration.py
@@ -175,7 +175,7 @@ class Enumeration:
                 query = rootQuery.inband.query
             value = inject.getValue(query, blind=False)
 
-            if value:
+            if not isNoneValue(value):
                 kb.data.cachedUsers = arrayizeValue(value)
 
         if not kb.data.cachedUsers and not conf.direct:
@@ -272,7 +272,7 @@ class Enumeration:
             else:
                 value = inject.getValue(query, blind=False)
 
-                if value:
+                if not isNoneValue(value):
                     for user, password in value:
                         if not user or user == " ":
                             continue
@@ -467,7 +467,7 @@ class Enumeration:
 
                 return self.getPrivileges(query2=True)
 
-            if values:
+            if not isNoneValue(values):
                 for value in values:
                     user = None
                     privileges = set()
@@ -683,7 +683,7 @@ class Enumeration:
                 query = rootQuery.inband.query
             value = inject.getValue(query, blind=False)
 
-            if value:
+            if not isNoneValue(value):
                 kb.data.cachedDbs = arrayizeValue(value)
 
         if not kb.data.cachedDbs and not conf.direct:
@@ -826,7 +826,7 @@ class Enumeration:
             value = inject.getValue(query, blind=False)
             value = filter(lambda x: x, value)
 
-            if value:
+            if not isNoneValue(value):
                 if Backend.isDbms(DBMS.SQLITE):
                     if isinstance(value, basestring):
                         value = [[ DBMS.SQLITE, value ]]
@@ -1073,12 +1073,12 @@ class Enumeration:
 
                 if Backend.isDbms(DBMS.SQLITE):
                     parseSqliteTableSchema(value)
-                elif value:
+                elif not isNoneValue(value):
                     table = {}
                     columns = {}
 
                     for columnData in value:
-                        if columnData[0] is not None:
+                        if not isNoneValue(columnData):
                             name = safeSQLIdentificatorNaming(columnData[0])
 
                             if len(columnData) == 1:
@@ -1836,7 +1836,7 @@ class Enumeration:
                 query += exclDbsQuery
                 values = inject.getValue(query, blind=False)
 
-                if values:
+                if not isNoneValue(values):
                     if isinstance(values, basestring):
                         values = [ values ]
 
@@ -1946,7 +1946,7 @@ class Enumeration:
                 query += exclDbsQuery
                 values = inject.getValue(query, blind=False)
 
-                if values:
+                if not isNoneValue(values):
                     if isinstance(values, basestring):
                         values = [ values ]
 
@@ -2109,7 +2109,7 @@ class Enumeration:
                 query += exclDbsQuery
                 values = inject.getValue(query, blind=False)
 
-                if values:
+                if not isNoneValue(values):
                     if isinstance(values, basestring):
                         values = [ values ]