diff --git a/lib/geos_extensions.rb b/lib/geos_extensions.rb
index <HASH>..<HASH> 100644
--- a/lib/geos_extensions.rb
+++ b/lib/geos_extensions.rb
@@ -16,7 +16,7 @@ module Geos
   autoload :ActiveRecord, File.join(GEOS_EXTENSIONS_BASE, 'active_record_extensions')
   autoload :GoogleMaps, File.join(GEOS_EXTENSIONS_BASE, 'google_maps')
 
-  REGEXP_WKT = /^(?:SRID=([0-9]+);)?(\s*[PLMCG].+)/i
+  REGEXP_WKT = /^(?:SRID=(-?[0-9]+);)?(\s*[PLMCG].+)/i
   REGEXP_WKB_HEX = /^[A-Fa-f0-9\s]+$/
   REGEXP_G_LAT_LNG_BOUNDS = /^
     \(
Allow for negative SRIDs.