diff --git a/src/phrases/abstractfieldphrase.cpp b/src/phrases/abstractfieldphrase.cpp
index 263b8e5..dafdc38 100644
--- a/src/phrases/abstractfieldphrase.cpp
+++ b/src/phrases/abstractfieldphrase.cpp
@@ -96,4 +96,11 @@ AbstractFieldPhrase AbstractFieldPhrase::operator ~()
     return f;
 }
 
+AbstractFieldPhrase AbstractFieldPhrase::operator !()
+{
+    AbstractFieldPhrase f(data->className, data->fieldName);
+    f.data->isNot = !data->isNot;
+    return f;
+}
+
 NUT_END_NAMESPACE
diff --git a/src/phrases/abstractfieldphrase.h b/src/phrases/abstractfieldphrase.h
index 0078fe6..c40d58c 100644
--- a/src/phrases/abstractfieldphrase.h
+++ b/src/phrases/abstractfieldphrase.h
@@ -57,6 +57,7 @@ public:
     ConditionalPhrase operator >=(const AbstractFieldPhrase &other);
 
     AbstractFieldPhrase operator ~();
+    AbstractFieldPhrase operator !();
     AssignmentPhrase operator =(const QVariant &other);
     AssignmentPhrase operator =(const ConditionalPhrase &other);
     AssignmentPhrase operator <<(const QVariant &other);