diff --git a/lib/core/settings.py b/lib/core/settings.py
index d07816ec9..70e9340ea 100644
--- a/lib/core/settings.py
+++ b/lib/core/settings.py
@@ -19,7 +19,7 @@ from lib.core.enums import OS
 from lib.core.revision import getRevisionNumber
 
 # sqlmap version (<major>.<minor>.<month>.<monthly commit>)
-VERSION = "1.0.9.19"
+VERSION = "1.0.9.20"
 REVISION = getRevisionNumber()
 TYPE = "dev" if VERSION.count('.') > 2 and VERSION.split('.')[-1] != '0' else "stable"
 TYPE_COLORS = {"dev": 33, "stable": 90, "pip": 34}
diff --git a/lib/techniques/blind/inference.py b/lib/techniques/blind/inference.py
index 20a96474e..4b02587f7 100644
--- a/lib/techniques/blind/inference.py
+++ b/lib/techniques/blind/inference.py
@@ -66,6 +66,7 @@ def bisection(payload, expression, length=None, charsetType=None, firstChar=None
     finalValue = None
     retrievedLength = 0
     asciiTbl = getCharset(charsetType)
+    threadData = getCurrentThreadData()
     timeBasedCompare = (kb.technique in (PAYLOAD.TECHNIQUE.TIME, PAYLOAD.TECHNIQUE.STACKED))
     retVal = hashDBRetrieve(expression, checkConf=True)
 
@@ -254,9 +255,43 @@ def bisection(payload, expression, length=None, charsetType=None, firstChar=None
 
             maxChar = maxValue = charTbl[-1]
             minChar = minValue = charTbl[0]
+            firstCheck = False
+            lastCheck = False
 
             while len(charTbl) != 1:
-                position = (len(charTbl) >> 1)
+                position = None
+
+                if charsetType is None:
+                    if not firstCheck:
+                        try:
+                            try:
+                                lastChar = [_ for _ in threadData.shared.value if _ is not None][-1]
+                            except IndexError:
+                                lastChar = None
+                            if 'a' <= lastChar <= 'z':
+                                position = charTbl.index(ord('a') - 1)  # 96
+                            elif 'A' <= lastChar <= 'Z':
+                                position = charTbl.index(ord('A') - 1)  # 64
+                            elif '0' <= lastChar <= '9':
+                                position = charTbl.index(ord('0') - 1)  # 47
+                        except ValueError:
+                            pass
+                        finally:
+                            firstCheck = True
+
+                    elif not lastCheck:
+                        if charTbl[(len(charTbl) >> 1)] < ord(' '):
+                            try:
+                                # favorize last char check if current value inclines toward 0
+                                position = charTbl.index(1)
+                            except ValueError:
+                                pass
+                            finally:
+                                lastCheck = True
+
+                if position is None:
+                    position = (len(charTbl) >> 1)
+
                 posValue = charTbl[position]
                 falsePayload = None
 
@@ -376,8 +411,6 @@ def bisection(payload, expression, length=None, charsetType=None, firstChar=None
 
         # Go multi-threading (--threads > 1)
         if conf.threads > 1 and isinstance(length, int) and length > 1:
-            threadData = getCurrentThreadData()
-
             threadData.shared.value = [None] * length
             threadData.shared.index = [firstChar]    # As list for python nested function scoping
             threadData.shared.start = firstChar
@@ -476,6 +509,7 @@ def bisection(payload, expression, length=None, charsetType=None, firstChar=None
         # No multi-threading (--threads = 1)
         else:
             index = firstChar
+            threadData.shared.value = ""
 
             while True:
                 index += 1
@@ -551,7 +585,7 @@ def bisection(payload, expression, length=None, charsetType=None, firstChar=None
                 if kb.data.processChar:
                     val = kb.data.processChar(val)
 
-                partialValue += val
+                threadData.shared.value = partialValue = partialValue + val
 
                 if showEta:
                     progress.progress(time.time() - charStart, index)
diff --git a/txt/checksum.md5 b/txt/checksum.md5
index a0146fa5f..204cca0f7 100644
--- a/txt/checksum.md5
+++ b/txt/checksum.md5
@@ -45,7 +45,7 @@ e60456db5380840a586654344003d4e6  lib/core/readlineng.py
 5ef56abb8671c2ca6ceecb208258e360  lib/core/replication.py
 99a2b496b9d5b546b335653ca801153f  lib/core/revision.py
 7c15dd2777af4dac2c89cab6df17462e  lib/core/session.py
-b160ccb31688ecf1c91d62ed0de26a9f  lib/core/settings.py
+95276012feeed6d7d2dc6f22724c70cc  lib/core/settings.py
 7af83e4f18cab6dff5e67840eb65be80  lib/core/shell.py
 23657cd7d924e3c6d225719865855827  lib/core/subprocessng.py
 0bc2fae1dec18cdd11954b22358293f2  lib/core/target.py
@@ -87,7 +87,7 @@ cc9c82cfffd8ee9b25ba3af6284f057e  lib/takeover/__init__.py
 7d6cd7bdfc8f4bc4e8aed60c84cdf87f  lib/takeover/udf.py
 f6e3084abd506925a8be3d1c0a6d058c  lib/takeover/web.py
 9af83a62de360184f1c14e69b8a95cfe  lib/takeover/xp_cmdshell.py
-927092550c89f8c3c5caad2b14af0830  lib/techniques/blind/inference.py
+f9fccc94cb9d5c15f84b5feb579ab0de  lib/techniques/blind/inference.py
 cc9c82cfffd8ee9b25ba3af6284f057e  lib/techniques/blind/__init__.py
 cc9c82cfffd8ee9b25ba3af6284f057e  lib/techniques/brute/__init__.py
 d36effffe64e63ef9b3be490f850e2cc  lib/techniques/brute/use.py