diff --git a/extra/vulnserver/vulnserver.py b/extra/vulnserver/vulnserver.py
index b5175711b..ebde61ce5 100644
--- a/extra/vulnserver/vulnserver.py
+++ b/extra/vulnserver/vulnserver.py
@@ -147,16 +147,21 @@ class ReqHandler(BaseHTTPRequestHandler):
                             _cursor.execute("SELECT * FROM users WHERE id=%s LIMIT 0, 1" % self.params["id"])
                         results = _cursor.fetchall()
 
-                    output += "<b>SQL results:</b>\n"
-                    output += "<table border=\"1\">\n"
+                    output += "<b>SQL results:</b><br>\n"
 
-                    for row in results:
-                        output += "<tr>"
-                        for value in row:
-                            output += "<td>%s</td>" % value
-                        output += "</tr>\n"
+                    if results:
+                        output += "<table border=\"1\">\n"
+
+                        for row in results:
+                            output += "<tr>"
+                            for value in row:
+                                output += "<td>%s</td>" % value
+                            output += "</tr>\n"
+
+                        output += "</table>\n"
+                    else:
+                        output += "no results found"
 
-                    output += "</table>\n"
                     output += "</body></html>"
                 except Exception as ex:
                     code = INTERNAL_SERVER_ERROR
diff --git a/lib/controller/checks.py b/lib/controller/checks.py
index cf934a753..883767ae0 100644
--- a/lib/controller/checks.py
+++ b/lib/controller/checks.py
@@ -939,6 +939,9 @@ def checkFalsePositives(injection):
                 if conf.string and any(conf.string in getUnicode(_) for _ in (randInt1, randInt2, randInt3)):
                     continue
 
+                if conf.notString and any(conf.notString in getUnicode(_) for _ in (randInt1, randInt2, randInt3)):
+                    continue
+
                 if randInt3 > randInt2 > randInt1:
                     break
 
diff --git a/lib/core/settings.py b/lib/core/settings.py
index 37fa380c8..6b7f01f9c 100644
--- a/lib/core/settings.py
+++ b/lib/core/settings.py
@@ -18,7 +18,7 @@ from lib.core.enums import OS
 from thirdparty.six import unichr as _unichr
 
 # sqlmap version (<major>.<minor>.<month>.<monthly commit>)
-VERSION = "1.4.5.3"
+VERSION = "1.4.5.4"
 TYPE = "dev" if VERSION.count('.') > 2 and VERSION.split('.')[-1] != '0' else "stable"
 TYPE_COLORS = {"dev": 33, "stable": 90, "pip": 34}
 VERSION_STRING = "sqlmap/%s#%s" % ('.'.join(VERSION.split('.')[:-1]) if VERSION.count('.') > 2 and VERSION.split('.')[-1] == '0' else VERSION, TYPE)
diff --git a/lib/core/testing.py b/lib/core/testing.py
index 6568fb3da..b779be244 100644
--- a/lib/core/testing.py
+++ b/lib/core/testing.py
@@ -48,6 +48,7 @@ def vulnTest():
         ("-r <request> --flush-session -v 5 --test-skip='heavy' --save=<tmp>", ("CloudFlare", "possible DBMS: 'SQLite'", "User-agent: foobar", "~Type: time-based blind")),
         ("-l <log> --flush-session --keep-alive --skip-waf -v 5 --technique=U --union-from=users --banner --parse-errors", ("banner: '3.", "ORDER BY term out of range", "~xp_cmdshell", "Connection: keep-alive")),
         ("-l <log> --offline --banner -v 5", ("banner: '3.", "~[TRAFFIC OUT]")),
+        ("-u <url> --flush-session --banner --technique=B --not-string 'no results'", ("banner: '3.",)),
         ("-u <url> --flush-session --banner --technique=B --first=1 --last=2", ("banner: '3.'",)),
         ("-u <url> --flush-session --encoding=ascii --forms --crawl=2 --threads=2 --banner", ("total of 2 targets", "might be injectable", "Type: UNION query", "banner: '3.")),
         ("-u <url> --flush-session --data='{\"id\": 1}' --banner", ("might be injectable", "3 columns", "Payload: {\"id\"", "Type: boolean-based blind", "Type: time-based blind", "Type: UNION query", "banner: '3.")),
diff --git a/lib/request/comparison.py b/lib/request/comparison.py
index 90fb14c53..29c32893c 100644
--- a/lib/request/comparison.py
+++ b/lib/request/comparison.py
@@ -63,13 +63,19 @@ def _comparison(page, headers, code, getRatioValue, pageLength):
     if any((conf.string, conf.notString, conf.regexp)):
         rawResponse = "%s%s" % (listToStrValue(_ for _ in headers.headers if not _.startswith("%s:" % URI_HTTP_HEADER)) if headers else "", page)
 
-        # String to match in page when the query is True and/or valid
+        # String to match in page when the query is True
         if conf.string:
             return conf.string in rawResponse
 
-        # String to match in page when the query is False and/or invalid
+        # String to match in page when the query is False
         if conf.notString:
-            return conf.notString not in rawResponse
+            if conf.notString in rawResponse:
+                return False
+            else:
+                if kb.errorIsNone and (wasLastResponseDBMSError() or wasLastResponseHTTPError()):
+                    return None
+                else:
+                    return True
 
         # Regular expression to match in page when the query is True and/or valid
         if conf.regexp: