diff --git a/BUILD.gn b/BUILD.gn
index 46c4b28..4743753 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -47,6 +47,9 @@
 }
 
 spirv_tools_dir = glslang_spirv_tools_dir
+if (!defined(glslang_angle)) {
+  glslang_angle = false
+}
 
 config("glslang_public") {
   include_dirs = [ "." ]