diff --git a/tools/tests.py b/tools/tests.py
index 687a2d649c..4164d45202 100644
--- a/tools/tests.py
+++ b/tools/tests.py
@@ -17,6 +17,7 @@ limitations under the License.
 from tools.paths import *
 from tools.data.support import *
 from argparse import ArgumentTypeError
+from utils import columnate
 
 try:
     import tools.private_settings as ps
@@ -1223,7 +1224,7 @@ TEST_MAP = dict([(test['id'], Test(i)) for i, test in enumerate(TESTS)])
 def test_known(string):
     i = int(string)
     if i >= 0 and i < len(TESTS) : return i
-    else : raise ArgumentTypeError("{0} does not index a test. The accepted range is 0 to {1}".format(i, len(TEST_MAP) - 1))
+    else : raise ArgumentTypeError("{0} does not index a test. The accepted range is 0 to {1}\nThe test mapping is:\n{2}".format(i, len(TEST_MAP) - 1, columnate([str(i) + ":" + t['id'] for i,t in zip(range(len(TESTS)), TESTS)])))
 
 def test_name_known(string):
     nlist = string.split(',')
@@ -1231,6 +1232,6 @@ def test_name_known(string):
         if test_id not in TEST_MAP.keys():
             if getattr(ps, "test_alias", None) is None or \
                ps.test_alias.get(test_id, "") not in TEST_MAP.keys():
-                raise ArgumentTypeError("Program with name '{0}' not found. Supported tests are {1}".format(test_id, ", ".join(TEST_MAP.keys())))
+                raise ArgumentTypeError("Program with name '{0}' not found. Supported tests are: \n{1}".format(test_id, columnate([t['id'] for t in TESTS])))
 
     return [TEST_MAP[n].n for n in nlist]
diff --git a/tools/utils.py b/tools/utils.py
index c2c2f7141f..6ffca38c9f 100644
--- a/tools/utils.py
+++ b/tools/utils.py
@@ -18,6 +18,7 @@ import sys
 import inspect
 import os
 import argparse
+import math
 from os import listdir, remove, makedirs
 from shutil import copyfile
 from os.path import isdir, join, exists, split, relpath, splitext
@@ -209,7 +210,7 @@ def argparse_type(casedness, prefer_hyphen=False) :
             elif string not in list and newstring in list:
                 raise argparse.ArgumentTypeError("{0} is not a supported {1}. Did you mean {2}?".format(string, type_name, newstring))
             else:
-                raise argparse.ArgumentTypeError("{0} is not a supported {1}. Supported {1}s are {2}.".format(string, type_name, ", ".join(list)))
+                raise argparse.ArgumentTypeError("{0} is not a supported {1}. Supported {1}s are:\n{2}".format(string, type_name, columnate(list)))
         return parse_type
     return middle
 
@@ -226,3 +227,19 @@ def argparse_many(fn):
 def argparse_filestring_type(string) :
     if exists(string) : return string
     else : raise argparse.ArgumentTypeError("{0} does not exist in the filesystem.".format(string))
+
+def columnate(strings, seperator=", ", chars=80):
+    col_width = max(len(s) for s in strings)
+    total_width = col_width + len(seperator)
+    columns = math.floor(chars / total_width)
+    output = ""
+    for i, s in zip(range(len(strings)), strings):
+        append = s
+        if i != len(strings) - 1:
+            append += seperator
+        if i % columns == columns - 1:
+            append += "\n"
+        else:
+            append = append.ljust(total_width)
+        output += append
+    return output