diff --git a/tests/data/Makefile.inc b/tests/data/Makefile.inc
index bd897a5ab..35446cf71 100644
--- a/tests/data/Makefile.inc
+++ b/tests/data/Makefile.inc
@@ -136,7 +136,7 @@ test1288 \
 test1298 test1299 \
 test1300 test1301 test1302 test1303 test1304 test1305 test1306 test1307 \
 test1308 test1309 test1310 test1311 test1312 test1313 test1314 test1315 \
-test1316 test1317 test1318 test1319 test1320 test1321 test1322          \
+test1316 test1317 test1318 test1319 test1320 test1321 test1322 test1323 \
          test1325 test1326 test1327 test1328 test1329 test1330 test1331 \
 test1332 test1333 test1334 test1335 test1336 test1337 test1338 test1339 \
 test1340 test1341 test1342 test1343 test1344 test1345 test1346 test1347 \
diff --git a/tests/data/test1323 b/tests/data/test1323
new file mode 100644
index 000000000..c5e598cc4
--- /dev/null
+++ b/tests/data/test1323
@@ -0,0 +1,32 @@
+<testcase>
+<info>
+<keywords>
+unittest
+curlx_tvdiff
+</keywords>
+</info>
+
+#
+# Server-side
+<reply>
+</reply>
+
+#
+# Client-side
+<client>
+<server>
+none
+</server>
+<name>
+curlx_tvdiff
+</name>
+<tool>
+unit1323
+</tool>
+</client>
+
+#
+# Verify data after the test has been "shot"
+<verify>
+</verify>
+</testcase>
diff --git a/tests/unit/Makefile.inc b/tests/unit/Makefile.inc
index 1320b4a67..bfb5c4d45 100644
--- a/tests/unit/Makefile.inc
+++ b/tests/unit/Makefile.inc
@@ -6,7 +6,8 @@ UNITFILES = curlcheck.h \
 
 # These are all unit test programs
 UNITPROGS = unit1300 unit1301 unit1302 unit1303 unit1304 unit1305 unit1307	\
- unit1308 unit1309 unit1330 unit1394 unit1395 unit1396 unit1397 unit1398	\
+ unit1308 unit1309 unit1323 \
+ unit1330 unit1394 unit1395 unit1396 unit1397 unit1398	\
  unit1399	\
  unit1600 unit1601 unit1602 unit1603 unit1604 unit1605 unit1606
 
@@ -37,6 +38,9 @@ unit1308_CPPFLAGS = $(AM_CPPFLAGS)
 unit1309_SOURCES = unit1309.c $(UNITFILES)
 unit1309_CPPFLAGS = $(AM_CPPFLAGS)
 
+unit1323_SOURCES = unit1323.c $(UNITFILES)
+unit1323_CPPFLAGS = $(AM_CPPFLAGS)
+
 unit1330_SOURCES = unit1330.c $(UNITFILES)
 unit1330_CPPFLAGS = $(AM_CPPFLAGS)
 
diff --git a/tests/unit/unit1323.c b/tests/unit/unit1323.c
new file mode 100644
index 000000000..65dd3d287
--- /dev/null
+++ b/tests/unit/unit1323.c
@@ -0,0 +1,66 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+#include "curlcheck.h"
+
+#include "timeval.h"
+
+static CURLcode unit_setup(void)
+{
+  return CURLE_OK;
+}
+
+static void unit_stop(void)
+{
+
+}
+
+struct a {
+  struct curltime first;
+  struct curltime second;
+  time_t result;
+};
+
+UNITTEST_START
+{
+  struct a tests[] = {
+    { {36762, 8345 }, {36761, 995926 }, 13 },
+    { {36761, 995926 }, {36762, 8345 }, -13 },
+    { {36761, 995926 }, {0, 0}, 36761995 },
+    { {0, 0}, {36761, 995926 }, -36761995 },
+  };
+  size_t i;
+
+  for(i=0; i < sizeof(tests)/sizeof(tests[0]); i++) {
+    time_t result = curlx_tvdiff(tests[i].first, tests[i].second);
+    if(result != tests[i].result) {
+      printf("%d.%06u to %d.%06u got %d, but expected %d\n",
+             tests[i].first.tv_sec,
+             tests[i].first.tv_usec,
+             tests[i].second.tv_sec,
+             tests[i].second.tv_usec,
+             result,
+             tests[i].result);
+      fail("unexpected result!");
+    }
+  }
+}
+UNITTEST_STOP