diff --git a/lib/request/inject.py b/lib/request/inject.py
index cdf320054..56e2849b8 100644
--- a/lib/request/inject.py
+++ b/lib/request/inject.py
@@ -204,7 +204,7 @@ def __goInferenceProxy(expression, fromUser=False, batch=False, unpack=True, cha
         # (or similar depending on the back-end DBMS) can return
         # multiple entries
         if limitCond:
-            if limitRegExp:
+            if limitRegExp and stopLimit is not None:
                 stopLimit = int(stopLimit)
 
                 # From now on we need only the expression until the " LIMIT "
diff --git a/plugins/dbms/access/enumeration.py b/plugins/dbms/access/enumeration.py
index 3bc035bb3..2b55cceac 100644
--- a/plugins/dbms/access/enumeration.py
+++ b/plugins/dbms/access/enumeration.py
@@ -49,7 +49,7 @@ class Enumeration(GenericEnumeration):
         return {}
 
     def getDbs(self):
-        warnMsg = "on Microsoft Access it is not possible to enumerate databases"
+        warnMsg = "on Microsoft Access it is not possible to enumerate databases (use only '--tables')"
         logger.warn(warnMsg)
 
         return []
diff --git a/plugins/dbms/firebird/enumeration.py b/plugins/dbms/firebird/enumeration.py
index cd055f8cf..3e1de64fc 100644
--- a/plugins/dbms/firebird/enumeration.py
+++ b/plugins/dbms/firebird/enumeration.py
@@ -13,7 +13,7 @@ class Enumeration(GenericEnumeration):
         GenericEnumeration.__init__(self)
 
     def getDbs(self):
-        warnMsg = "on Firebird it is not possible to enumerate databases"
+        warnMsg = "on Firebird it is not possible to enumerate databases (use only '--tables')"
         logger.warn(warnMsg)
 
         return []
diff --git a/plugins/dbms/sqlite/enumeration.py b/plugins/dbms/sqlite/enumeration.py
index 9cf6ebf0b..89b377277 100644
--- a/plugins/dbms/sqlite/enumeration.py
+++ b/plugins/dbms/sqlite/enumeration.py
@@ -44,7 +44,7 @@ class Enumeration(GenericEnumeration):
         return {}
 
     def getDbs(self):
-        warnMsg = "on SQLite it is not possible to enumerate databases"
+        warnMsg = "on SQLite it is not possible to enumerate databases (use only '--tables')"
         logger.warn(warnMsg)
 
         return []