diff --git a/src/providers/postgres/qgspostgresconn.cpp b/src/providers/postgres/qgspostgresconn.cpp
index c938f070ac0f..4563e088fa99 100644
--- a/src/providers/postgres/qgspostgresconn.cpp
+++ b/src/providers/postgres/qgspostgresconn.cpp
@@ -1183,15 +1183,15 @@ QString QgsPostgresConn::fieldExpression( const QgsField &fld, QString expr )
   expr = expr.arg( quotedIdentifier( fld.name() ) );
   if ( type == "money" )
   {
-    return QString( "cash_out(%1)" ).arg( expr );
+    return QString( "cash_out(%1)::text" ).arg( expr );
   }
   else if ( type.startsWith( "_" ) )
   {
-    return QString( "array_out(%1)" ).arg( expr );
+    return QString( "array_out(%1)::text" ).arg( expr );
   }
   else if ( type == "bool" )
   {
-    return QString( "boolout(%1)" ).arg( expr );
+    return QString( "boolout(%1)::text" ).arg( expr );
   }
   else if ( type == "geometry" )
   {
diff --git a/src/providers/postgres/qgspostgresprovider.cpp b/src/providers/postgres/qgspostgresprovider.cpp
index f89950928039..fb9b95cdbbef 100644
--- a/src/providers/postgres/qgspostgresprovider.cpp
+++ b/src/providers/postgres/qgspostgresprovider.cpp
@@ -1270,8 +1270,7 @@ void QgsPostgresProvider::uniqueValues( int index, QList<QVariant> &uniqueValues
       sql += QString( " WHERE %1" ).arg( mSqlWhereClause );
     }
 
-    sql +=  QString( " ORDER BY %1" )
-            .arg( quotedIdentifier( fld.name() ) );
+    sql +=  QString( " ORDER BY %1" ).arg( connectionRO()->fieldExpression( fld ) );
 
     if ( limit >= 0 )
     {