diff --git a/src/test/include.am b/src/test/include.am
index f7c0204832d..762216e6dc3 100644
--- a/src/test/include.am
+++ b/src/test/include.am
@@ -96,6 +96,7 @@ src_test_test_SOURCES = \
 	src/test/test_status.c \
 	src/test/test_threads.c \
 	src/test/test_util.c \
+	src/test/test_util_format.c \
 	src/test/test_helpers.c \
         src/test/test_dns.c \
 	src/test/testing_common.c \
diff --git a/src/test/test.c b/src/test/test.c
index e10e2602669..aff7d8e048d 100644
--- a/src/test/test.c
+++ b/src/test/test.c
@@ -1158,6 +1158,7 @@ extern struct testcase_t socks_tests[];
 extern struct testcase_t status_tests[];
 extern struct testcase_t thread_tests[];
 extern struct testcase_t util_tests[];
+extern struct testcase_t util_format_tests[];
 extern struct testcase_t dns_tests[];
 
 struct testgroup_t testgroups[] = {
@@ -1203,9 +1204,9 @@ struct testgroup_t testgroups[] = {
   { "socks/", socks_tests },
   { "status/" , status_tests },
   { "util/", util_tests },
+  { "util/format/", util_format_tests },
   { "util/logging/", logging_tests },
   { "util/thread/", thread_tests },
   { "dns/", dns_tests },
   END_OF_GROUPS
 };
-
diff --git a/src/test/test_util_format.c b/src/test/test_util_format.c
new file mode 100644
index 00000000000..8ffc2de63c6
--- /dev/null
+++ b/src/test/test_util_format.c
@@ -0,0 +1,197 @@
+/* Copyright (c) 2010-2015, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#include "orconfig.h"
+#include "or.h"
+
+#include "test.h"
+
+#define UTIL_FORMAT_PRIVATE
+#include "util_format.h"
+
+#define NS_MODULE util_format
+
+static void
+test_util_format_base64_encode(void *ignored)
+{
+  (void)ignored;
+  int res;
+  int i;
+  char *src;
+  char *dst;
+
+  src = tor_malloc_zero(256);
+  dst = tor_malloc_zero(1000);
+
+  for(i=0;i<256;i++) {
+    src[i] = (char)i;
+  }
+
+  res = base64_encode(NULL, 1, src, 1, 0);
+  tt_int_op(res, OP_EQ, -1);
+
+  res = base64_encode(dst, 1, NULL, 1, 0);
+  tt_int_op(res, OP_EQ, -1);
+
+  res = base64_encode(dst, 1, src, 10, 0);
+  tt_int_op(res, OP_EQ, -1);
+
+  res = base64_encode(dst, SSIZE_MAX-1, src, 1, 0);
+  tt_int_op(res, OP_EQ, -1);
+
+  res = base64_encode(dst, SSIZE_MAX-1, src, 10, 0);
+  tt_int_op(res, OP_EQ, -1);
+
+  res = base64_encode(dst, 1000, src, 256, 0);
+  tt_int_op(res, OP_EQ, 344);
+  tt_str_op(dst, OP_EQ, "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygpKissLS4vMDEyMzQ1Njc4OTo7PD0+P0BBQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWltcXV5fYGFiY2RlZmdoaWprbG1ub3BxcnN0dXZ3eHl6e3x9fn+AgYKDhIWGh4iJiouMjY6PkJGSk5SVlpeYmZqbnJ2en6ChoqOkpaanqKmqq6ytrq+wsbKztLW2t7i5uru8vb6/wMHCw8TFxsfIycrLzM3Oz9DR0tPU1dbX2Nna29zd3t/g4eLj5OXm5+jp6uvs7e7v8PHy8/T19vf4+fr7/P3+/w==");
+
+
+  res = base64_encode(dst, 1000, src, 256, BASE64_ENCODE_MULTILINE);
+  tt_int_op(res, OP_EQ, 350);
+  tt_str_op(dst, OP_EQ, "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygpKissLS4v\n"
+            "MDEyMzQ1Njc4OTo7PD0+P0BBQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWltcXV5f\n"
+            "YGFiY2RlZmdoaWprbG1ub3BxcnN0dXZ3eHl6e3x9fn+AgYKDhIWGh4iJiouMjY6P\n"
+            "kJGSk5SVlpeYmZqbnJ2en6ChoqOkpaanqKmqq6ytrq+wsbKztLW2t7i5uru8vb6/\n"
+            "wMHCw8TFxsfIycrLzM3Oz9DR0tPU1dbX2Nna29zd3t/g4eLj5OXm5+jp6uvs7e7v\n"
+            "8PHy8/T19vf4+fr7/P3+/w==\n");
+
+  res = base64_encode(dst, 1000, src+1, 255, BASE64_ENCODE_MULTILINE);
+  tt_int_op(res, OP_EQ, 346);
+
+  for(i = 0;i<50;i++) {
+    src[i] = 0;
+  }
+  src[50] = 255;
+  src[51] = 255;
+  src[52] = 255;
+  src[53] = 255;
+
+  res = base64_encode(dst, 1000, src, 54, BASE64_ENCODE_MULTILINE);
+  tt_int_op(res, OP_EQ, 74);
+
+  res = base64_encode(dst, 1000, src+1, 53, BASE64_ENCODE_MULTILINE);
+  tt_int_op(res, OP_EQ, 74);
+
+  res = base64_encode(dst, 1000, src+2, 52, BASE64_ENCODE_MULTILINE);
+  tt_int_op(res, OP_EQ, 74);
+
+  res = base64_encode(dst, 1000, src+3, 51, BASE64_ENCODE_MULTILINE);
+  tt_int_op(res, OP_EQ, 70);
+
+  res = base64_encode(dst, 1000, src+4, 50, BASE64_ENCODE_MULTILINE);
+  tt_int_op(res, OP_EQ, 70);
+
+  res = base64_encode(dst, 1000, src+5, 49, BASE64_ENCODE_MULTILINE);
+  tt_int_op(res, OP_EQ, 70);
+
+  res = base64_encode(dst, 1000, src+6, 48, BASE64_ENCODE_MULTILINE);
+  tt_int_op(res, OP_EQ, 65);
+
+  res = base64_encode(dst, 1000, src+7, 47, BASE64_ENCODE_MULTILINE);
+  tt_int_op(res, OP_EQ, 65);
+
+  res = base64_encode(dst, 1000, src+8, 46, BASE64_ENCODE_MULTILINE);
+  tt_int_op(res, OP_EQ, 65);
+
+
+ done:
+  tor_free(src);
+  tor_free(dst);
+}
+
+static void
+test_util_format_base64_decode_nopad(void *ignored)
+{
+  (void)ignored;
+  int res;
+  int i;
+  char *src;
+  uint8_t *dst;
+
+  src = tor_malloc_zero(256);
+  dst = tor_malloc_zero(1000);
+
+  for(i=0;i<256;i++) {
+    src[i] = (char)i;
+  }
+
+  res = base64_decode_nopad(dst, 1, src, SIZE_T_CEILING);
+  tt_int_op(res, OP_EQ, -1);
+
+  res = base64_decode_nopad(dst, 1, src, 5);
+  tt_int_op(res, OP_EQ, -1);
+
+ done:
+  tor_free(src);
+  tor_free(dst);
+}
+
+
+static void
+test_util_format_base64_decode(void *ignored)
+{
+  (void)ignored;
+  int res;
+  int i;
+  char *src;
+  char *dst;
+
+  src = tor_malloc_zero(256);
+  dst = tor_malloc_zero(1000);
+
+  for(i=0;i<256;i++) {
+    src[i] = (char)i;
+  }
+
+  res = base64_decode(dst, 1, src, SIZE_T_CEILING);
+  tt_int_op(res, OP_EQ, -1);
+
+  res = base64_decode(dst, SIZE_T_CEILING+1, src, 10);
+  tt_int_op(res, OP_EQ, -1);
+
+ done:
+  tor_free(src);
+  tor_free(dst);
+}
+
+
+
+static void
+test_util_format_base16_decode(void *ignored)
+{
+  (void)ignored;
+  int res;
+  int i;
+  char *src;
+  char *dst;
+
+  src = tor_malloc_zero(256);
+  dst = tor_malloc_zero(1000);
+
+  for(i=0;i<256;i++) {
+    src[i] = (char)i;
+  }
+
+  res = base16_decode(dst, 3, src, 3);
+  tt_int_op(res, OP_EQ, -1);
+
+  res = base16_decode(dst, 1, src, 10);
+  tt_int_op(res, OP_EQ, -1);
+
+  res = base16_decode(dst, SIZE_T_CEILING+2, src, 10);
+  tt_int_op(res, OP_EQ, -1);
+
+ done:
+  tor_free(src);
+  tor_free(dst);
+}
+
+
+struct testcase_t util_format_tests[] = {
+  { "base64_encode", test_util_format_base64_encode, 0, NULL, NULL },
+  { "base64_decode_nopad", test_util_format_base64_decode_nopad, 0, NULL, NULL },
+  { "base64_decode", test_util_format_base64_decode, 0, NULL, NULL },
+  { "base16_decode", test_util_format_base16_decode, 0, NULL, NULL },
+  END_OF_TESTCASES
+};