diff --git a/src/gui/util/qvalidator.cpp b/src/gui/util/qvalidator.cpp
index f71a66c98c..8be08ebd2a 100644
--- a/src/gui/util/qvalidator.cpp
+++ b/src/gui/util/qvalidator.cpp
@@ -658,7 +658,11 @@ QValidator::State QDoubleValidatorPrivate::validateWithLocale(QString &input, QL
     if (notation == QDoubleValidator::StandardNotation) {
         double max = qMax(qAbs(q->b), qAbs(q->t));
         qlonglong v;
-        if (convertDoubleTo(max, &v)) {
+        // Need a whole number to pass to convertDoubleTo() or it fails. Use
+        // floor, as max is positive so this has the same number of digits
+        // before the decimal point, where qCeil() might take us up to a power
+        // of ten, adding a digit.
+        if (convertDoubleTo(qFloor(max), &v)) {
             qlonglong n = pow10(numDigits(v));
             // In order to get the highest possible number in the intermediate
             // range we need to get 10 to the power of the number of digits
diff --git a/tests/auto/gui/util/qdoublevalidator/tst_qdoublevalidator.cpp b/tests/auto/gui/util/qdoublevalidator/tst_qdoublevalidator.cpp
index 7818e83f09..225ac14c7f 100644
--- a/tests/auto/gui/util/qdoublevalidator/tst_qdoublevalidator.cpp
+++ b/tests/auto/gui/util/qdoublevalidator/tst_qdoublevalidator.cpp
@@ -143,6 +143,7 @@ void tst_QDoubleValidator::validate_data()
     QTest::newRow("data56") << "C" << 1229.0 << 1231.0 << -1 << QString("123E+") << ITM << INV;
     QTest::newRow("data57") << "C" << 1229.0 << 1231.0 << -1 << QString("123E+1") << ACC << INV;
     QTest::newRow("data58") << "C" << 0.0 << 100.0 << -1 << QString("0.0") << ACC << ACC;
+    QTest::newRow("overlong") << "C" << 0.0 << 99.9 << 2 << QString("1234.0") << ITM << INV;
 
     QTest::newRow("data_de0")  << "de" << 0.0 << 100.0 << 1 << QString("50,0") << ACC << ACC;
     QTest::newRow("data_de1")  << "de" << 00.0 << 100.0 << 1 << QString("500,0") << ITM << ITM;