diff --git a/Makefile.frag b/Makefile.frag
index 6755000..0a4d98d 100644
--- a/Makefile.frag
+++ b/Makefile.frag
@@ -1,3 +1,4 @@
+PHP_TEST_SHARED_EXTENSIONS+=-d extension=$(EXTENSION_DIR)/json.so
 
 testv8: all
 	$(PHP_EXECUTABLE) -n -d extension_dir=./modules -d extension=v8js.so test.php