diff --git a/lib/core/common.py b/lib/core/common.py
index f132a1ef9..eb8543e78 100644
--- a/lib/core/common.py
+++ b/lib/core/common.py
@@ -71,6 +71,7 @@ from lib.core.settings import DUMP_TAB_MARKER
 from lib.core.settings import DUMP_START_MARKER
 from lib.core.settings import DUMP_STOP_MARKER
 from lib.core.settings import MIN_TIME_RESPONSES
+from lib.core.settings import TIME_STDEV_COEFF
 
 class UnicodeRawConfigParser(RawConfigParser):
     """
@@ -1595,7 +1596,7 @@ def wasLastRequestDelayed():
             warnMsg += "with less than %d response times" % MIN_TIME_RESPONSES
             logger.warn(warnMsg)
 
-        return (threadData.lastQueryDuration >= average(kb.responseTimes) + 7 * deviation)
+        return (threadData.lastQueryDuration >= average(kb.responseTimes) + TIME_STDEV_COEFF * deviation)
     else:
         return threadData.lastQueryDuration - conf.timeSec
 
diff --git a/lib/core/settings.py b/lib/core/settings.py
index 67315e4f2..12f7ea9c6 100644
--- a/lib/core/settings.py
+++ b/lib/core/settings.py
@@ -49,7 +49,8 @@ DUMP_STOP_MARKER    = "__STOP__"
 PAYLOAD_DELIMITER   = "\x00"
 CHAR_INFERENCE_MARK = "%c"
 
-UNKNOWN_DBMS_VERSION = "Unknown"
+# coefficient used for a time-based query delay checking (must be >= 7)
+TIME_STDEV_COEFF    = 10
 
 # suffix used for naming meta databases in DBMS(es) without explicit database name
 METADB_SUFFIX       = "_masterdb"
@@ -60,6 +61,9 @@ MIN_TIME_RESPONSES  = 15
 # after these number of blanks at the end inference should stop (just in case)
 INFERENCE_BLANK_BREAK = 10
 
+# string used for representation of unknown dbms version
+UNKNOWN_DBMS_VERSION = "Unknown"
+
 # System variables
 IS_WIN             = subprocess.mswindows
 # The name of the operating system dependent module imported. The following