diff --git a/doc/19_contour.md b/doc/19_contour.md
index b29ed89..fdee52e 100644
--- a/doc/19_contour.md
+++ b/doc/19_contour.md
@@ -18,7 +18,7 @@ Function to generate a contour map from an scatter dataset of points, using one
 | method   | integer     | 0:nearest neighbor, 1: barycentric, 2: IDW|
 | classmethod   | integer     | 0:equals, 1: heads&tails, 2:jenks, 3:quantiles |
 | steps   | integer     | Number of steps in the classification|
-| resolution   | integer     | if <= 0: max processing time in seconds (smart resolution) , if >0: resolution in meters
+| max_time   | integer     | if <= 0: max processing time in seconds (smart resolution) , if >0: resolution in meters
 
 ### Returns
 Returns a table object
diff --git a/src/pg/sql/19_contour.sql b/src/pg/sql/19_contour.sql
index 18430c0..78f0cfd 100644
--- a/src/pg/sql/19_contour.sql
+++ b/src/pg/sql/19_contour.sql
@@ -21,6 +21,9 @@ DECLARE
 BEGIN
 
     -- nasty trick to override issue #121
+    IF max_time = 0 THEN
+        max_time = -90;
+    END IF;
     resolution := max_time;
     max_time := -1 * resolution;