diff --git a/bin/ruby-build b/bin/ruby-build
old mode 100755
new mode 100644
index d5cad32671..e6fd63b7e4
--- a/bin/ruby-build
+++ b/bin/ruby-build
@@ -3,6 +3,10 @@
 set -E
 exec 3<&2 # preserve original stderr at fd 3
 
+resolve_link() {
+  $(type -p greadlink readlink | head -1) $1
+}
+
 abs_dirname() {
   local cwd="$(pwd)"
   local path="$1"
@@ -10,7 +14,7 @@ abs_dirname() {
   while [ -n "$path" ]; do
     cd "${path%/*}"
     local name="${path##*/}"
-    path="$(readlink "$name" || true)"
+    path="$(resolve_link "$name" || true)"
   done
 
   pwd