--- jmemansi.c.orig	1996-01-06 23:29:46.000000000 +0000
+++ jmemansi.c	2006-04-23 10:54:09.812108600 +0100
@@ -12,6 +12,8 @@
  * is shoved onto the user.
  */
 
+#include <unistd.h>
+
 #define JPEG_INTERNALS
 #include "jinclude.h"
 #include "jpeglib.h"
@@ -157,7 +159,13 @@
 GLOBAL(long)
 jpeg_mem_init (j_common_ptr cinfo)
 {
-  return DEFAULT_MAX_MEM;	/* default for max_memory_to_use */
+    long phys_size;
+
+    if ((phys_size = sysconf(_SC_PHYS_PAGES)) == -1)
+        return DEFAULT_MAX_MEM; /* default for max_memory_to_use */
+    if ((phys_size *= sysconf(_SC_PAGESIZE)) < 0)
+        return DEFAULT_MAX_MEM;
+    return (long) (phys_size * 0.95);
 }
 
 GLOBAL(void)