diff --git a/ext/fiddle/lib/fiddle/pack.rb b/ext/fiddle/lib/fiddle/pack.rb
index 5467d3de4b..22eccedb76 100644
--- a/ext/fiddle/lib/fiddle/pack.rb
+++ b/ext/fiddle/lib/fiddle/pack.rb
@@ -48,7 +48,7 @@ module Fiddle
       ALIGN_MAP[TYPE_LONG_LONG] = ALIGN_MAP[-TYPE_LONG_LONG] = ALIGN_LONG_LONG
       PACK_MAP[TYPE_LONG_LONG] = PACK_MAP[-TYPE_LONG_LONG] = "q"
       SIZE_MAP[TYPE_LONG_LONG] = SIZE_MAP[-TYPE_LONG_LONG] = SIZEOF_LONG_LONG
-      PACK_MAP[TYPE_VOIDP] = PACK_MAP[TYPE_LONG_LONG] # override
+      PACK_MAP[TYPE_VOIDP] = "q" if SIZEOF_LONG_LONG == SIZEOF_VOIDP
     end
 
     def align(addr, align)