diff --git a/src/pg/sql/19_contour.sql b/src/pg/sql/19_contour.sql
index 784779e..ae48eb5 100644
--- a/src/pg/sql/19_contour.sql
+++ b/src/pg/sql/19_contour.sql
@@ -1,4 +1,4 @@
-DROP FUNCTION cdb_contour(geometry[],numeric[],numeric,integer,integer,integer,integer);
+DROP FUNCTION IF EXISTS cdb_contour(geometry[],numeric[],numeric,integer,integer,integer,integer);
 
 CREATE OR REPLACE FUNCTION CDB_Contour(
     IN geomin geometry[],