diff --git a/build-libcxx.sh b/build-libcxx.sh
index 8665e3f..bc09e4c 100755
--- a/build-libcxx.sh
+++ b/build-libcxx.sh
@@ -134,7 +134,7 @@ build_all() {
         mkdir -p build-$arch-$type
         cd build-$arch-$type
         if [ "$type" = "shared" ]; then
-            LIBCXXABI_VISIBILITY_FLAGS="-D_LIBCPP_BUILDING_LIBRARY -U_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS"
+            LIBCXXABI_VISIBILITY_FLAGS="-D_LIBCPP_BUILDING_LIBRARY= -U_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS"
         else
             LIBCXXABI_VISIBILITY_FLAGS="-D_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS"
         fi