diff --git a/build.sh b/build.sh
index ef85f23..1872038 100755
--- a/build.sh
+++ b/build.sh
@@ -120,7 +120,7 @@ if [ $f_res -eq 1 ]; then
     CONFFLAGS+="--with-libtapi=$TARGET_DIR "
   fi
   CONFFLAGS+="--with-libxar=$TARGET_DIR "
-  [ -z "$USE_CLANG_AS" ] && CONFFLAGS+="--disable-clang-as "
+  [ -n "$DISABLE_CLANG_AS" ] && CONFFLAGS+="--disable-clang-as "
   [ -n "$DISABLE_LTO_SUPPORT" ] && CONFFLAGS+="--disable-lto-support "
   # https://github.com/tpoechtrager/osxcross/issues/156
   CXX="$CXX -DNDEBUG" ./configure $CONFFLAGS