diff --git a/ChangeLog b/ChangeLog
index 5479e5c138..ae2fd73bae 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Wed Jan 29 13:00:17 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* util.c (ruby_qsort): fix potential stack overflow on a large
+	  machine.  based on the patch by Conrad Irwin <conrad.irwin AT
+	  gmail.com> at [ruby-core:51816].  [Bug #7772]
+
 Wed Jan 29 12:54:13 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* parse.y (local_push_gen, local_pop_gen): save cmdarg_stack to
diff --git a/util.c b/util.c
index ded3840804..2b8209d9da 100644
--- a/util.c
+++ b/util.c
@@ -278,7 +278,9 @@ ruby_qsort(void* base, const size_t nel, const size_t size,
   char *L = base;                    	/* left end of current region */
   char *R = (char*)base + size*(nel-1); /* right end of current region */
   size_t chklim = 63;                   /* threshold of ordering element check */
-  stack_node stack[32], *top = stack;   /* 32 is enough for 32bit CPU */
+  enum {size_bits = sizeof(size) * CHAR_BIT};
+  stack_node stack[size_bits];          /* enough for size_t size */
+  stack_node *top = stack;
   int mmkind;
   size_t high, low, n;
 
diff --git a/version.h b/version.h
index 88a8ec2ae5..68cee5b4ea 100644
--- a/version.h
+++ b/version.h
@@ -1,5 +1,5 @@
 #define RUBY_VERSION "1.9.3"
-#define RUBY_PATCHLEVEL 492
+#define RUBY_PATCHLEVEL 493
 
 #define RUBY_RELEASE_DATE "2014-01-29"
 #define RUBY_RELEASE_YEAR 2014