diff --git a/lib/rpl/core/program.rb b/lib/rpl/core/program.rb
index f7d14a8..3f8f7f0 100644
--- a/lib/rpl/core/program.rb
+++ b/lib/rpl/core/program.rb
@@ -12,7 +12,11 @@ module RplLang
                               proc do
                                 args = stack_extract( [:any] )
 
-                                run( args[0][:value].to_s )
+                                if %i[list string numeric boolean].include?( args[0][:type] )
+                                  @stack << args[0] # these types evaluate to themselves
+                                else
+                                  run( args[0][:value].to_s )
+                                end
                               end )
       end
     end