diff --git a/chef/lib/chef/provider/group/usermod.rb b/chef/lib/chef/provider/group/usermod.rb
index dd2911f34b8..21010e2b435 100644
--- a/chef/lib/chef/provider/group/usermod.rb
+++ b/chef/lib/chef/provider/group/usermod.rb
@@ -31,7 +31,7 @@ def load_current_resource
 
         def modify_group_members
           case node[:platform]
-          when "openbsd", "netbsd"
+          when "openbsd", "netbsd", "aix"
             append_flags = "-G"
           when "solaris"
             append_flags = "-a -G"