diff --git a/doc/THANKS b/doc/THANKS
index 00a2f9164..52037e867 100644
--- a/doc/THANKS
+++ b/doc/THANKS
@@ -639,6 +639,9 @@ ragos <ragos@joker.ms>
 shiftzwei <shiftzwei@gmail.com>
     for reporting a couple of bugs
 
+smith <esmyl911@gmail.com>
+    for reporting a minor bug
+
 Stuffe <stuffe.dk@gmail.com>
     for reporting a minor bug and a feature request
 
diff --git a/lib/core/option.py b/lib/core/option.py
index faff2c4d9..ebad2b6c2 100644
--- a/lib/core/option.py
+++ b/lib/core/option.py
@@ -104,6 +104,7 @@ from lib.core.settings import LOCALHOST
 from lib.core.settings import MAX_NUMBER_OF_THREADS
 from lib.core.settings import PARAMETER_SPLITTING_REGEX
 from lib.core.settings import TIME_DELAY_CANDIDATES
+from lib.core.settings import UNION_CHAR_REGEX
 from lib.core.settings import UNKNOWN_DBMS_VERSION
 from lib.core.settings import WEBSCARAB_SPLITTER
 from lib.core.update import update
@@ -1811,6 +1812,10 @@ def __basicOptionValidation():
         errMsg = "value for --time-sec option must be an integer greater than 0"
         raise sqlmapSyntaxException, errMsg
 
+    if conf.uChar and not re.match(UNION_CHAR_REGEX, conf.uChar):
+        errMsg = "value for --union-char option must be an alpha-numeric value (e.g. 1)"
+        raise sqlmapSyntaxException, errMsg
+
     if isinstance(conf.uCols, basestring):
         if not conf.uCols.isdigit() and ("-" not in conf.uCols or len(conf.uCols.split("-")) != 2):
             errMsg = "value for --union-cols must be a range with hyphon "
diff --git a/lib/core/settings.py b/lib/core/settings.py
index 4c5c7fe33..1f56cfae9 100644
--- a/lib/core/settings.py
+++ b/lib/core/settings.py
@@ -397,3 +397,6 @@ MAX_TIME_REVALIDATION_STEPS = 5
 
 # Characters that can be used to split parameter values in provided command line (e.g. in --tamper)
 PARAMETER_SPLITTING_REGEX = r'[,|;]'
+
+# Regular expression describing possible union char value (e.g. used in --union-char)
+UNION_CHAR_REGEX = r'\A\w+\Z'