diff --git a/superfields/src/main/java/org/vaadin/miki/superfields/numbers/AbstractSuperNumberField.java b/superfields/src/main/java/org/vaadin/miki/superfields/numbers/AbstractSuperNumberField.java
index bfc4fe5f..6a9c91d6 100644
--- a/superfields/src/main/java/org/vaadin/miki/superfields/numbers/AbstractSuperNumberField.java
+++ b/superfields/src/main/java/org/vaadin/miki/superfields/numbers/AbstractSuperNumberField.java
@@ -291,7 +291,7 @@ private void updateRegularExpression() {
         this.field.setPattern(this.regexp);
 
         LOGGER.debug("pattern updated to {}", this.regexp);
-        if(!this.isNegativeValueAllowed() && this.negativityPredicate.test(value)) {
+        if(!this.isNegativeValueAllowed() && value != null && this.negativityPredicate.test(value)) {
             LOGGER.debug("negative values are not allowed, so turning into positive value {}", value);
             this.setValue(this.turnToPositiveOperator.apply(value));
         }
diff --git a/superfields/src/test/java/org/vaadin/miki/superfields/numbers/BaseTestsForIntegerNumbers.java b/superfields/src/test/java/org/vaadin/miki/superfields/numbers/BaseTestsForIntegerNumbers.java
index efd1f472..fe95777f 100644
--- a/superfields/src/test/java/org/vaadin/miki/superfields/numbers/BaseTestsForIntegerNumbers.java
+++ b/superfields/src/test/java/org/vaadin/miki/superfields/numbers/BaseTestsForIntegerNumbers.java
@@ -200,6 +200,37 @@ public void testNullWithNullAllowed() {
         Assert.assertTrue("null representation must be an empty string", this.getField().getRawValue().isEmpty());
     }
 
+    @Test
+    public void testNullWithNullAllowedAndNegativeNotAllowed() {
+        this.getField().setNullValueAllowed(true);
+        this.getField().setNegativeValueAllowed(false);
+        this.getField().setValue(null);
+        T value = this.getField().getValue();
+        Assert.assertNull("value was set to null and it must be null", value);
+        Assert.assertTrue("null representation must be an empty string", this.getField().getRawValue().isEmpty());
+    }
+
+    @Test
+    public void testNullWithNullAllowedAndNegativeAllowed() {
+        this.getField().setNullValueAllowed(true);
+        this.getField().setNegativeValueAllowed(true);
+        this.getField().setValue(null);
+        T value = this.getField().getValue();
+        Assert.assertNull("value was set to null and it must be null", value);
+        Assert.assertTrue("null representation must be an empty string", this.getField().getRawValue().isEmpty());
+    }
+
+    @Test
+    public void testNullAllowedSetNullThenChangeRegexp() {
+        this.getField().setNullValueAllowed(true);
+        this.getField().setValue(null);
+        this.getField().setNegativeValueAllowed(!this.getField().isNegativeValueAllowed());
+        T value = this.getField().getValue();
+        Assert.assertNull("value was set to null and it must be null", value);
+        Assert.assertTrue("null representation must be an empty string", this.getField().getRawValue().isEmpty());
+    }
+
+
     @Test(expected = IllegalArgumentException.class)
     public void testNullWithNoNullAllowedThrowsException() {
         // by default, there should be no allowance for null values