diff --git a/geocoder/admin0/extension/.gitignore b/geocoder/admin0/extension/.gitignore
new file mode 100644
index 0000000..fbca225
--- /dev/null
+++ b/geocoder/admin0/extension/.gitignore
@@ -0,0 +1 @@
+results/
diff --git a/geocoder/admin0/extension/Makefile b/geocoder/admin0/extension/Makefile
index 62b397a..cf92715 100644
--- a/geocoder/admin0/extension/Makefile
+++ b/geocoder/admin0/extension/Makefile
@@ -1,5 +1,6 @@
 EXTENSION = cdb_geocoder_admin0
 DATA = cdb_geocoder_admin0--0.0.1.sql
+REGRESS = cdb_geocoder_admin0_test
 
 # postgres build stuff
 PG_CONFIG = pg_config
diff --git a/geocoder/admin0/extension/expected/cdb_geocoder_admin0_test.out b/geocoder/admin0/extension/expected/cdb_geocoder_admin0_test.out
new file mode 100644
index 0000000..834ab14
--- /dev/null
+++ b/geocoder/admin0/extension/expected/cdb_geocoder_admin0_test.out
@@ -0,0 +1,13 @@
+CREATE EXTENSION postgis;
+CREATE EXTENSION schema_triggers;
+CREATE EXTENSION plpythonu;
+CREATE EXTENSION cartodb;
+CREATE EXTENSION cdb_geocoder_admin0;
+-- Check that the synonym function is callable, should return NULL
+SELECT (admin0_synonym_lookup(Array['United States', 'ESP'])).*;
+       q       | adm0_a3 
+---------------+---------
+ United States | 
+ ESP           | 
+(2 rows)
+
diff --git a/geocoder/admin0/extension/sql/cdb_geocoder_admin0_test.sql b/geocoder/admin0/extension/sql/cdb_geocoder_admin0_test.sql
new file mode 100644
index 0000000..c5fe53f
--- /dev/null
+++ b/geocoder/admin0/extension/sql/cdb_geocoder_admin0_test.sql
@@ -0,0 +1,8 @@
+CREATE EXTENSION postgis;
+CREATE EXTENSION schema_triggers;
+CREATE EXTENSION plpythonu;
+CREATE EXTENSION cartodb;
+CREATE EXTENSION cdb_geocoder_admin0;
+
+-- Check that the synonym function is callable, should return NULL
+SELECT (admin0_synonym_lookup(Array['United States', 'ESP'])).*;