kmx.io/rbpkg

diff --git a/lib/rbpkg/repos/libffi.rb b/lib/rbpkg/repos/libffi.rb
index a1013c4..69fd7e4 100644
--- a/lib/rbpkg/repos/libffi.rb
+++ b/lib/rbpkg/repos/libffi.rb
@@ -9,7 +9,11 @@ class Rbpkg::Repos::Libffi < Rbpkg::Repo
   end
 
   def configure_env
-    "MAKE=gmake"
+    if system("which gmake >/dev/null 2>&1")
+      "MAKE=gmake"
+    else
+      super
+    end
   end
 
   def dir