diff --git a/apps/openmw/mwdialogue/filter.cpp b/apps/openmw/mwdialogue/filter.cpp
index 7b5f354a23..8e8ac4db5e 100644
--- a/apps/openmw/mwdialogue/filter.cpp
+++ b/apps/openmw/mwdialogue/filter.cpp
@@ -136,8 +136,12 @@ bool MWDialogue::Filter::testDisposition (const ESM::DialInfo& info, bool invert
 
 bool MWDialogue::Filter::testSelectStruct (const SelectWrapper& select) const
 {
-    if (select.isNpcOnly() && mActor.getTypeName()!=typeid (ESM::NPC).name())
-        return select.isInverted();
+    if (select.isNpcOnly() && (mActor.getTypeName() != typeid (ESM::NPC).name()))
+        // If the actor is a creature, we do not test the conditions applicable
+        // only to NPCs. Such conditions can never be satisfied, apart
+        // inverted ones (NotClass, NotRace, NotFaction return true
+        // because creatures are not of any race, class or faction).
+        return select.getType() == SelectWrapper::Type_Inverted;
 
     switch (select.getType())
     {
@@ -145,6 +149,9 @@ bool MWDialogue::Filter::testSelectStruct (const SelectWrapper& select) const
         case SelectWrapper::Type_Integer: return select.selectCompare (getSelectStructInteger (select));
         case SelectWrapper::Type_Numeric: return testSelectStructNumeric (select);
         case SelectWrapper::Type_Boolean: return select.selectCompare (getSelectStructBoolean (select));
+
+        // We must not do the comparison for inverted functions (eg. Function_NotClass)
+        case SelectWrapper::Type_Inverted: return getSelectStructBoolean (select);
     }
 
     return true;
diff --git a/apps/openmw/mwdialogue/selectwrapper.cpp b/apps/openmw/mwdialogue/selectwrapper.cpp
index 77930ae423..81a4153601 100644
--- a/apps/openmw/mwdialogue/selectwrapper.cpp
+++ b/apps/openmw/mwdialogue/selectwrapper.cpp
@@ -219,7 +219,6 @@ MWDialogue::SelectWrapper::Type MWDialogue::SelectWrapper::getType() const
     static const Function booleanFunctions[] =
     {
         Function_False,
-        Function_NotId, Function_NotFaction, Function_NotClass, Function_NotRace, Function_NotCell,
         Function_SameGender, Function_SameRace, Function_SameFaction,
         Function_PcCommonDisease, Function_PcBlightDisease, Function_PcCorprus,
         Function_PcExpelled,
@@ -231,6 +230,13 @@ MWDialogue::SelectWrapper::Type MWDialogue::SelectWrapper::getType() const
         Function_None // end marker
     };
 
+    static const Function invertedBooleanFunctions[] =
+    {
+        Function_NotId, Function_NotFaction, Function_NotClass,
+        Function_NotRace, Function_NotCell,
+        Function_None // end marker
+    };
+
     Function function = getFunction();
 
     for (int i=0; integerFunctions[i]!=Function_None; ++i)
@@ -245,16 +251,13 @@ MWDialogue::SelectWrapper::Type MWDialogue::SelectWrapper::getType() const
         if (booleanFunctions[i]==function)
             return Type_Boolean;
 
+    for (int i=0; invertedBooleanFunctions[i]!=Function_None; ++i)
+        if (invertedBooleanFunctions[i]==function)
+            return Type_Inverted;
+
     return Type_None;
 }
 
-bool MWDialogue::SelectWrapper::isInverted() const
-{
-    char type = mSelect.mSelectRule[1];
-
-    return type=='7' || type=='8' || type=='9' || type=='A' || type=='B' || type=='C';
-}
-
 bool MWDialogue::SelectWrapper::isNpcOnly() const
 {
     static const Function functions[] =
@@ -283,17 +286,17 @@ bool MWDialogue::SelectWrapper::isNpcOnly() const
 
 bool MWDialogue::SelectWrapper::selectCompare (int value) const
 {
-    return selectCompareImp (mSelect, value)!=isInverted(); // logic XOR
+    return selectCompareImp (mSelect, value);
 }
 
 bool MWDialogue::SelectWrapper::selectCompare (float value) const
 {
-    return selectCompareImp (mSelect, value)!=isInverted(); // logic XOR
+    return selectCompareImp (mSelect, value);
 }
 
 bool MWDialogue::SelectWrapper::selectCompare (bool value) const
 {
-    return selectCompareImp (mSelect, static_cast<int> (value))!=isInverted(); // logic XOR
+    return selectCompareImp (mSelect, static_cast<int> (value));
 }
 
 std::string MWDialogue::SelectWrapper::getName() const
diff --git a/apps/openmw/mwdialogue/selectwrapper.hpp b/apps/openmw/mwdialogue/selectwrapper.hpp
index c27339afa0..0548c60cbb 100644
--- a/apps/openmw/mwdialogue/selectwrapper.hpp
+++ b/apps/openmw/mwdialogue/selectwrapper.hpp
@@ -50,7 +50,8 @@ namespace MWDialogue
                 Type_None,
                 Type_Integer,
                 Type_Numeric,
-                Type_Boolean
+                Type_Boolean,
+                Type_Inverted
             };
 
         private:
@@ -67,8 +68,6 @@ namespace MWDialogue
 
             Type getType() const;
 
-            bool isInverted() const;
-
             bool isNpcOnly() const;
             ///< \attention Do not call any of the select functions for this select struct!