diff --git a/project.gyp b/project.gyp
index 5e79eba6..a64c7061 100644
--- a/project.gyp
+++ b/project.gyp
@@ -106,6 +106,7 @@
       ],
       'sources': [
         'src/runtime/document.c',
+        'src/runtime/language.c',
         'src/runtime/lexer.c',
         'src/runtime/node.c',
         'src/runtime/stack.c',