diff --git a/lib/controller/action.py b/lib/controller/action.py
index 8b18c3b2b..a7e82f92b 100644
--- a/lib/controller/action.py
+++ b/lib/controller/action.py
@@ -46,6 +46,9 @@ def action():
         if htmlParsed and htmlParsed.lower() in SUPPORTED_DBMS:
             errMsg += ". Do not specify the back-end DBMS manually, "
             errMsg += "sqlmap will fingerprint the DBMS for you"
+        elif kb.nullConnection:
+            errMsg += ". You can try to rerun without using optimization "
+            errMsg += "switch '%s'" % ("-o" if conf.optimize else "--null-connection")
         else:
             errMsg += ". Support for this DBMS will be implemented at "
             errMsg += "some point"
diff --git a/lib/controller/checks.py b/lib/controller/checks.py
index cac433f54..7ee10918d 100644
--- a/lib/controller/checks.py
+++ b/lib/controller/checks.py
@@ -54,8 +54,6 @@ def checkSqlInjection(place, parameter, value, parenthesis):
     postfix = ""
     retVal = None
 
-    conf.matchRatio = None
-
     if conf.prefix or conf.postfix:
         if conf.prefix:
             prefix = conf.prefix
@@ -98,6 +96,12 @@ def checkSqlInjection(place, parameter, value, parenthesis):
     return retVal
 
 def heuristicCheckSqlInjection(place, parameter, value):
+    if kb.nullConnection:
+        debugMsg  = "heuristic checking skipped "
+        debugMsg += "because NULL connection used"
+        logger.debug(debugMsg)
+        return
+
     prefix = ""
     postfix = ""
 
@@ -135,24 +139,19 @@ def checkDynParam(place, parameter, value):
 
     randInt = randomInt()
     payload = agent.payload(place, parameter, value, getUnicode(randInt))
-    dynResult1 = Request.queryPage(payload, place)
+    dynResult = Request.queryPage(payload, place)
 
-    if True == dynResult1:
+    if True == dynResult:
         return False
 
     infoMsg = "confirming that %s parameter '%s' is dynamic" % (place, parameter)
     logger.info(infoMsg)
 
-    payload = agent.payload(place, parameter, value, "'%s" % randomStr())
-    dynResult2 = Request.queryPage(payload, place)
+    randInt = randomInt()
+    payload = agent.payload(place, parameter, value, getUnicode(randInt))
+    dynResult = Request.queryPage(payload, place)
 
-    payload = agent.payload(place, parameter, value, "\"%s" % randomStr())
-    dynResult3 = Request.queryPage(payload, place)
-
-    condition  = True != dynResult2
-    condition |= True != dynResult3
-
-    return condition
+    return not dynResult
 
 def checkDynamicContent(firstPage, secondPage):
     """
diff --git a/lib/controller/controller.py b/lib/controller/controller.py
index c7b17c819..889fa91ad 100644
--- a/lib/controller/controller.py
+++ b/lib/controller/controller.py
@@ -209,6 +209,8 @@ def start():
                     checkStability()
 
                 for place in conf.parameters.keys():
+                    conf.matchRatio = None
+
                     if not conf.paramDict.has_key(place):
                         continue
 
diff --git a/lib/request/comparison.py b/lib/request/comparison.py
index 0aacf95c1..b3d02d89d 100644
--- a/lib/request/comparison.py
+++ b/lib/request/comparison.py
@@ -102,6 +102,9 @@ def comparison(page, headers=None, getSeqMatcher=False, pageLength=None):
     elif wasLastRequestError():
         return False
 
+    elif ratio == 1:
+        return True
+
     # If the url is not stable it returns sequence matcher between the
     # first untouched HTTP response page content and this content
     else: