diff --git a/captcha.py b/captcha.py
index f1a050113..47456a65b 100644
--- a/captcha.py
+++ b/captcha.py
@@ -124,12 +124,23 @@ def gen_subdir(basedir, md5hash, levels):
 			os.mkdir(fulldir)
 	return subdir
 
-def try_pick_word(words, blacklist, verbose):
+def try_pick_word(words, blacklist, verbose, min_length, max_length):
 	word1 = words[random.randint(0,len(words)-1)]
 	word2 = words[random.randint(0,len(words)-1)]
 	word = word1+word2
 	if verbose:
 		print "word is %s" % word
+
+	if len(word) < min_length:
+		if verbose:
+			print "skipping word pair '%s' because it has fewer than %d characters" % (word, min_length)
+		return None
+
+	if max_length > 0 and len(word) > max_length:
+		if verbose:
+			print "skipping word pair '%s' because it has more than %d characters" % (word, max_length)
+		return None
+
 	if nonalpha.search(word):
 		if verbose:
 			print "skipping word pair '%s' because it contains non-alphabetic characters" % word
@@ -142,9 +153,9 @@ def try_pick_word(words, blacklist, verbose):
 			return None
 	return word
 
-def pick_word(words, blacklist, verbose):
+def pick_word(words, blacklist, verbose, min_length, max_length):
 	for x in range(1000): # If we can't find a valid combination in 1000 tries, just give up
-		word = try_pick_word(words, blacklist, verbose)
+		word = try_pick_word(words, blacklist, verbose, min_length, max_length)
 		if word:
 			return word
 	sys.exit("Unable to find valid word combinations")
@@ -170,7 +181,9 @@ if __name__ == '__main__':
 	parser.add_option("--blacklist", help="A blacklist of words that should not be used", metavar="FILE")
 	parser.add_option("--fill", help="Fill the output directory to contain N files, overrides count, cannot be used with --dirs", metavar="N", type='int')
 	parser.add_option("--dirs", help="Put the images into subdirectories N levels deep - $wgCaptchaDirectoryLevels", metavar="N", type='int')
-	parser.add_option("--verbose", "-v", help="Show debugging information", action='store_true')	
+	parser.add_option("--verbose", "-v", help="Show debugging information", action='store_true')
+	parser.add_option("--min-length", help="Minimum length for a captcha challenge", type='int', default=1)
+	parser.add_option("--max-length", help="Maximum length for a captcha challenge", type='int', default=-1)
 	
 	opts, args = parser.parse_args()
 
@@ -197,7 +210,7 @@ if __name__ == '__main__':
 	dirs = opts.dirs
 	verbose = opts.verbose
 	fontsize = opts.font_size
-	
+
 	if fill:
 		count = max(0, fill - len(os.listdir(output)))
 	
@@ -212,7 +225,7 @@ if __name__ == '__main__':
 		blacklist = []
 	
 	for i in range(count):
-		word = pick_word(words, blacklist, verbose)
+		word = pick_word(words, blacklist, verbose, opts.min_length, opts.max_length)
 		salt = "%08x" % random.randrange(2**32)
 		# 64 bits of hash is plenty for this purpose
 		md5hash = hashlib.md5(key+salt+word+key+salt).hexdigest()[:16]