diff --git a/hibernate-core/src/main/java/org/hibernate/dialect/aggregate/PostgreSQLAggregateSupport.java b/hibernate-core/src/main/java/org/hibernate/dialect/aggregate/PostgreSQLAggregateSupport.java
index 4c207e117a..74f0adf4f5 100644
--- a/hibernate-core/src/main/java/org/hibernate/dialect/aggregate/PostgreSQLAggregateSupport.java
+++ b/hibernate-core/src/main/java/org/hibernate/dialect/aggregate/PostgreSQLAggregateSupport.java
@@ -16,7 +16,6 @@ import org.hibernate.mapping.Column;
 import org.hibernate.metamodel.mapping.JdbcMapping;
 import org.hibernate.metamodel.mapping.SelectableMapping;
 import org.hibernate.metamodel.mapping.SelectablePath;
-import org.hibernate.sql.Template;
 import org.hibernate.sql.ast.SqlAstNodeRenderingMode;
 import org.hibernate.sql.ast.SqlAstTranslator;
 import org.hibernate.sql.ast.spi.SqlAppender;
@@ -305,7 +304,7 @@ public class PostgreSQLAggregateSupport extends AggregateSupportImpl {
 				this.customWriteExpressionEnd = "";
 			}
 			else {
-				final String[] parts = StringHelper.split( ".", customWriteExpression );
+				final String[] parts = StringHelper.split( "?", customWriteExpression );
 				assert parts.length == 2;
 				this.customWriteExpressionStart = parts[0];
 				this.customWriteExpressionEnd = parts[1];