diff --git a/plugins/dbms/mysql/fingerprint.py b/plugins/dbms/mysql/fingerprint.py
index a9e5e6adc..abd502898 100644
--- a/plugins/dbms/mysql/fingerprint.py
+++ b/plugins/dbms/mysql/fingerprint.py
@@ -280,7 +280,10 @@ class Fingerprint(GenericFingerprint):
         elif result is False:
             kb.os = "Windows"
 
-        infoMsg = "the back-end DBMS operating system is %s" % (kb.os or "Unknown")
-        logger.info(infoMsg)
+        if kb.os:
+            infoMsg = "the back-end DBMS operating system is %s" % kb.os
+            logger.info(infoMsg)
+        else:
+            self.userChooseDbmsOs()
 
         self.cleanup(onlyFileTbl=True)
diff --git a/plugins/generic/fingerprint.py b/plugins/generic/fingerprint.py
index 23aa44755..793640235 100644
--- a/plugins/generic/fingerprint.py
+++ b/plugins/generic/fingerprint.py
@@ -7,7 +7,9 @@ Copyright (c) 2006-2010 sqlmap developers (http://sqlmap.sourceforge.net/)
 See the file 'doc/COPYING' for copying permission
 """
 
+from lib.core.common import readInput
 from lib.core.data import kb
+from lib.core.data import logger
 from lib.core.exception import sqlmapUndefinedMethod
 
 class Fingerprint:
@@ -35,3 +37,23 @@ class Fingerprint:
 
     def forceDbmsEnum(self):
         pass
+
+    def userChooseDbmsOs(self):
+        warnMsg = "for some reason sqlmap was unable to fingerprint "
+        warnMsg += "the back-end DBMS operating system"
+        logger.warn(warnMsg)
+
+        msg = "do you want to provide the OS? [(W)indows/(l)inux]"
+
+        while True:
+            os = readInput(msg, default="W")
+
+            if os[0].lower() == "w":
+                kb.os = "Windows"
+                break
+            elif os[0].lower() == "l":
+                kb.os = "Linux"
+                break
+            else:
+                warnMsg = "invalid value"
+                logger.warn(warnMsg)