diff --git a/chrono/datetime.cpp b/chrono/datetime.cpp
index 9f9430d..f2b9913 100644
--- a/chrono/datetime.cpp
+++ b/chrono/datetime.cpp
@@ -171,10 +171,11 @@ std::pair<DateTime, TimeSpan> DateTime::fromIsoString(const char *str)
             } else {
                 ++valueIndex;
             }
-        } else if ((c == '+') && (++valueIndex == deltaHourIndex)) {
+        } else if ((c == '+') && (++valueIndex >= secondsIndex)) {
+            valueIndex = deltaHourIndex;
             deltaNegative = false;
-        } else if ((c == 'Z') && (++valueIndex == deltaHourIndex)) {
-            valueIndex += 2;
+        } else if ((c == 'Z') && (++valueIndex >= secondsIndex)) {
+            valueIndex = deltaHourIndex + 2;
         } else if (c == '\0') {
             break;
         } else {
diff --git a/tests/chronotests.cpp b/tests/chronotests.cpp
index 138007c..727ff09 100644
--- a/tests/chronotests.cpp
+++ b/tests/chronotests.cpp
@@ -159,6 +159,9 @@ void ChronoTests::testDateTime()
     // test further variants
     CPPUNIT_ASSERT_EQUAL_MESSAGE("Zulu time", TimeSpan(), DateTime::fromIsoString("2017-08-23T19:40:15.985077682Z").second);
     CPPUNIT_ASSERT_EQUAL_MESSAGE("no minutes", TimeSpan::fromHours(3), DateTime::fromIsoString("2017-08-23T19:40:15.985077682+03").second);
+    const auto test6 = DateTime::fromIsoString("1970-01-01T01:02:03+01:00");
+    CPPUNIT_ASSERT_EQUAL_MESSAGE("no seconds fraction", DateTime::fromDateAndTime(1970, 1, 1, 1, 2, 3), test6.first);
+    CPPUNIT_ASSERT_EQUAL_MESSAGE("no seconds fraction", TimeSpan::fromHours(1.0), test6.second);
     // test invalid characters
     CPPUNIT_ASSERT_THROW_MESSAGE("digits after Z", DateTime::fromIsoString("2017-O8-23T19:40:15.985077682Z02:00"), ConversionException);
     CPPUNIT_ASSERT_THROW_MESSAGE("invalid letter", DateTime::fromIsoString("2017-O8-23T19:40:15.985077682:+02:00"), ConversionException);