diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 48a5c5e84..e4ddbb744 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,13 @@
+2012-02-26  Corinna Vinschen  <corinna@vinschen.de>
+
+	* environ.cc (enum settings): Add setbool.  Rename justset to setdword
+	to avoid future problems.
+	(struct parse_thing): Change all justset to setbool for bool variables.
+	(parse_options): Add a case for setbool setting for bool variables
+	since justset (now setdword) always writes a DWORD value, thus
+	potentially overwriting adjacent memory locations.
+	* external.cc (cygwin_internal): Drop extern declaration.
+
 2012-02-26  Corinna Vinschen  <corinna@vinschen.de>
 
 	* environ.cc (dos_file_warning): Drop declaration.
diff --git a/winsup/cygwin/environ.cc b/winsup/cygwin/environ.cc
index a99f97cf8..33289d2f5 100644
--- a/winsup/cygwin/environ.cc
+++ b/winsup/cygwin/environ.cc
@@ -40,8 +40,9 @@ static NO_COPY bool export_settings = false;
 
 enum settings
   {
-    justset,
     isfunc,
+    setdword,
+    setbool,
     setbit
   };
 
@@ -111,16 +112,16 @@ static struct parse_thing
       } values[2];
   } known[] NO_COPY =
 {
-  {"detect_bloda", {&detect_bloda}, justset, NULL, {{false}, {true}}},
-  {"dosfilewarning", {&dos_file_warning}, justset, NULL, {{false}, {true}}},
+  {"detect_bloda", {&detect_bloda}, setbool, NULL, {{false}, {true}}},
+  {"dosfilewarning", {&dos_file_warning}, setbool, NULL, {{false}, {true}}},
   {"error_start", {func: error_start_init}, isfunc, NULL, {{0}, {0}}},
-  {"export", {&export_settings}, justset, NULL, {{false}, {true}}},
+  {"export", {&export_settings}, setbool, NULL, {{false}, {true}}},
   {"glob", {func: glob_init}, isfunc, NULL, {{0}, {s: "normal"}}},
   {"proc_retry", {func: set_proc_retry}, isfunc, NULL, {{0}, {5}}},
-  {"reset_com", {&reset_com}, justset, NULL, {{false}, {true}}},
+  {"reset_com", {&reset_com}, setbool, NULL, {{false}, {true}}},
   {"tty", {func: tty_is_gone}, isfunc, NULL, {{0}, {0}}},
-  {"winsymlinks", {&allow_winsymlinks}, justset, NULL, {{false}, {true}}},
-  {NULL, {0}, justset, 0, {{0}, {0}}}
+  {"winsymlinks", {&allow_winsymlinks}, setbool, NULL, {{false}, {true}}},
+  {NULL, {0}, setdword, 0, {{0}, {0}}}
 };
 
 /* Parse a string of the form "something=stuff somethingelse=more-stuff",
@@ -180,13 +181,20 @@ parse_options (const char *inbuf)
 		  k->values[istrue].s : eq);
 		debug_printf ("%s (called func)", k->name);
 		break;
-	      case justset:
+	      case setdword:
 		if (!istrue || !eq)
 		  *k->setting.x = k->values[istrue].i;
 		else
 		  *k->setting.x = strtol (eq, NULL, 0);
 		debug_printf ("%s %d", k->name, *k->setting.x);
 		break;
+	      case setbool:
+		if (!istrue || !eq)
+		  *k->setting.b = k->values[istrue].i;
+		else
+		  *k->setting.b = !!strtol (eq, NULL, 0);
+		debug_printf ("%s%s", *k->setting.b ? "" : "no", k->name);
+		break;
 	      case setbit:
 		*k->setting.x &= ~k->values[istrue].i;
 		if (istrue || (eq && strtol (eq, NULL, 0)))
diff --git a/winsup/cygwin/external.cc b/winsup/cygwin/external.cc
index 146dda953..cd86966b8 100644
--- a/winsup/cygwin/external.cc
+++ b/winsup/cygwin/external.cc
@@ -432,7 +432,6 @@ cygwin_internal (cygwin_getinfo_types t, ...)
 	break;
       case CW_SET_DOS_FILE_WARNING:
 	{
-	  extern bool dos_file_warning;
 	  dos_file_warning = va_arg (arg, int);
 	  res = 0;
 	}