diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 761df45fb..617f84a8d 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,9 @@
+2005-09-16  Christopher Faylor  <cgf@timesys.com>
+
+	* environ.cc (build_env): Clear envblock and return NULL on attempt to
+	use env var > 32K.
+	* spawn.cc (spawn_guts): Set E2BIG if build_env detects an error.
+
 2005-09-16  Christopher Faylor  <cgf@timesys.com>
 
 	* environ.cc (environ_init): Protect with a 'myfault' in case
diff --git a/winsup/cygwin/environ.cc b/winsup/cygwin/environ.cc
index 45e1ca7bd..b73c710a4 100644
--- a/winsup/cygwin/environ.cc
+++ b/winsup/cygwin/environ.cc
@@ -1034,6 +1034,12 @@ build_env (const char * const *envp, char *&envblock, int &envc,
 	    p = *srcp;		/* Don't worry about it */
 
 	  len = strlen (p);
+	  if (len >= 32 * 1024 * 1024)
+	    {
+	      free (envblock);
+	      envblock = NULL;
+	      break;
+	    }
 	  new_tl += len + 1;	/* Keep running total of block length so far */
 
 	  /* See if we need to increase the size of the block. */
@@ -1066,7 +1072,6 @@ build_env (const char * const *envp, char *&envblock, int &envc,
 					   of buffer */
     }
 
-
   debug_printf ("envp %p, envc %d", newenv, envc);
   return newenv;
 }
diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc
index ffafa8f7c..149a25999 100644
--- a/winsup/cygwin/spawn.cc
+++ b/winsup/cygwin/spawn.cc
@@ -624,6 +624,11 @@ spawn_guts (const char * prog_arg, const char *const *argv,
   cygheap->user.deimpersonate ();
 
   moreinfo->envp = build_env (envp, envblock, moreinfo->envc, real_path.iscygexec ());
+  if (!moreinfo->envp || !envblock)
+    {
+      set_errno (E2BIG);
+      goto out;
+    }
   ciresrv.set (chtype, real_path.iscygexec ());
   ciresrv.moreinfo = moreinfo;