diff --git a/utils/gn/secondary/lld/test/BUILD.gn b/utils/gn/secondary/lld/test/BUILD.gn
index 845d425..5268f2e 100644
--- a/utils/gn/secondary/lld/test/BUILD.gn
+++ b/utils/gn/secondary/lld/test/BUILD.gn
@@ -55,7 +55,7 @@
   if (llvm_enable_libxar) {
     extra_values += [ "HAVE_LIBXAR=1" ]
   } else {
-    extra_values += [ "HAVE_LIBXAR=" ]
+    extra_values += [ "HAVE_LIBXAR=0" ]  # Must be 0.
   }
 
   if (llvm_enable_libxml2) {