diff --git a/README.rdoc b/README.rdoc
index 2d79b3449ebbdaf7061b8be695e11492a09f8648..551c363e422e1603231b7b90703a2e460aaf561f 100644
--- a/README.rdoc
+++ b/README.rdoc
@@ -122,7 +122,7 @@ Some utility methods are also available:
    => 3619.77359999382
 
   # find the geographic center (aka center of gravity) of objects or points
-  Geocoder::Calculations.geographic_center(city1, city2, [40.22,-73.99], city4)
+  Geocoder::Calculations.geographic_center([city1, city2, [40.22,-73.99], city4])
    => [35.14968, -90.048929]
 
 Please see the code for more methods and detailed information about arguments (eg, working with kilometers).