diff --git a/src/blackmisc/propertyindexvariantmap.cpp b/src/blackmisc/propertyindexvariantmap.cpp
index 1b169e4a1..e09cb9181 100644
--- a/src/blackmisc/propertyindexvariantmap.cpp
+++ b/src/blackmisc/propertyindexvariantmap.cpp
@@ -30,17 +30,17 @@ namespace BlackMisc
     /*
      * ==
      */
-    bool CPropertyIndexVariantMap::operator ==(const CPropertyIndexVariantMap &other) const
+    bool operator ==(const CPropertyIndexVariantMap &a, const CPropertyIndexVariantMap &b)
     {
-        return this->m_wildcard == other.m_wildcard && this->m_values == other.m_values;
+        return a.m_wildcard == b.m_wildcard && a.m_values == b.m_values;
     }
 
     /*
      * !=
      */
-    bool CPropertyIndexVariantMap::operator !=(const CPropertyIndexVariantMap &other) const
+    bool operator !=(const CPropertyIndexVariantMap &a, const CPropertyIndexVariantMap &b)
     {
-        return !(*this == other);
+        return !(b == a);
     }
 
     /*
diff --git a/src/blackmisc/propertyindexvariantmap.h b/src/blackmisc/propertyindexvariantmap.h
index c08cf862d..dd2fd51a5 100644
--- a/src/blackmisc/propertyindexvariantmap.h
+++ b/src/blackmisc/propertyindexvariantmap.h
@@ -92,10 +92,10 @@ namespace BlackMisc
         void clear() { this->m_values.clear(); }
 
         //! Equal operator, required if maps are directly compared, not with CValueObject
-        bool operator ==(const CPropertyIndexVariantMap &other) const;
+        friend bool operator ==(const CPropertyIndexVariantMap &a, const CPropertyIndexVariantMap &b);
 
         //! Equal operator, required if maps are directly compared, not with CValueObject
-        bool operator !=(const CPropertyIndexVariantMap &other) const;
+        friend bool operator !=(const CPropertyIndexVariantMap &a, const CPropertyIndexVariantMap &b);
 
         //! Map
         const QMap<CPropertyIndex, CVariant> &map() const { return this->m_values; }