diff --git a/configure b/configure
index c519e40439..b87532b0c0 100755
--- a/configure
+++ b/configure
@@ -3168,7 +3168,7 @@ cc_check && _memalign=yes
 if test "$_memalign" = yes ; then
   def_memalign='#define HAVE_MEMALIGN 1'
 else
-  def_memalign='#undef HAVE_MEMALIGN'
+  def_memalign='#define HAVE_MEMALIGN 0'
   def_map_memalign='#define memalign(a,b) malloc(b)'
   darwin || def_memalign_hack='#define CONFIG_MEMALIGN_HACK 1'
 fi
diff --git a/liba52/liba52_changes.diff b/liba52/liba52_changes.diff
index 9a559a5036..0e9e71c53f 100644
--- a/liba52/liba52_changes.diff
+++ b/liba52/liba52_changes.diff
@@ -2354,7 +2354,8 @@
 +#include "mm_accel.h"
 +#include "libavutil/avutil.h"
  
- #ifdef HAVE_MEMALIGN
+-#ifdef HAVE_MEMALIGN
++#if HAVE_MEMALIGN
  /* some systems have memalign() but no declaration for it */
  void * memalign (size_t align, size_t size);
 -#else
diff --git a/liba52/parse.c b/liba52/parse.c
index 92d38b482f..fff01aed5b 100644
--- a/liba52/parse.c
+++ b/liba52/parse.c
@@ -39,7 +39,7 @@
 #include "mm_accel.h"
 #include "libavutil/avutil.h"
 
-#ifdef HAVE_MEMALIGN
+#if HAVE_MEMALIGN
 /* some systems have memalign() but no declaration for it */
 void * memalign (size_t align, size_t size);
 #endif