diff --git a/lib/geocoder/stores/active_record.rb b/lib/geocoder/stores/active_record.rb
index 91fabe05b126cfcb282a8e5f29140b543a38932a..1c0ab935366a87aa9dc021dacabc8dffbb01f941 100644
--- a/lib/geocoder/stores/active_record.rb
+++ b/lib/geocoder/stores/active_record.rb
@@ -45,7 +45,7 @@ module Geocoder::Store
             # If no lat/lon given we don't want any results, but we still
             # need distance and bearing columns so you can add, for example:
             # .order("distance")
-            select(select_clause(nil, "NULL", "NULL")).where(false_condition)
+            select(select_clause(nil, null_value, null_value)).where(false_condition)
           end
         }
 
@@ -64,7 +64,7 @@ module Geocoder::Store
               full_column_name(geocoder_options[:longitude])
             ))
           else
-            select(select_clause(nil, "NULL", "NULL")).where(false_condition)
+            select(select_clause(nil, null_value, null_value)).where(false_condition)
           end
         }
       end
@@ -224,6 +224,17 @@ module Geocoder::Store
         connection.adapter_name.match(/sqlite/i)
       end
 
+      def using_postgres?
+        connection.adapter_name.match(/postgres/i)
+      end
+
+      ##
+      # Use OID type when running in PosgreSQL
+      #
+      def null_value
+        using_postgres? ? 'NULL::text' : 'NULL'
+      end
+
       ##
       # Value which can be passed to where() to produce no results.
       #