diff --git a/.hgignore b/.hgignore
index 93d61940a..718d8872d 100644
--- a/.hgignore
+++ b/.hgignore
@@ -25,6 +25,7 @@ Makefile$
 ^pathnames\.h$
 ^src/sudo$
 ^src/sesh$
+^src/check_ttyname$
 ^src/sudo_usage\.h$
 
 ^compat/mksiglist$
diff --git a/MANIFEST b/MANIFEST
index 6ae6fd4d8..b92a2169e 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -242,7 +242,7 @@ plugins/sudoers/po/nl.mo
 plugins/sudoers/po/nl.po
 plugins/sudoers/po/pl.mo
 plugins/sudoers/po/pl.po
-plugins/sudoers/po/sl.mo  
+plugins/sudoers/po/sl.mo
 plugins/sudoers/po/sl.po
 plugins/sudoers/po/sudoers.pot
 plugins/sudoers/po/sv.mo
@@ -411,6 +411,7 @@ src/po/vi.po
 src/po/zh_CN.mo
 src/po/zh_CN.po
 src/preload.c
+src/regress/ttyname/check_ttyname.c
 src/selinux.c
 src/sesh.c
 src/signal.c
diff --git a/src/Makefile.in b/src/Makefile.in
index 93fe043dc..efd435821 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -75,6 +75,10 @@ install_gid = 0
 # File mode to use for shared libraries/objects
 shlib_mode = @SHLIB_MODE@
 
+TEST_PROGS = check_ttyname
+TEST_LIBS = @LIBS@ @LIBINTL@ $(LT_LIBS)
+TEST_LDFLAGS = @LDFLAGS@
+
 # OS dependent defines
 DEFS = @OSDEFS@ -DLOCALEDIR=\"$(localedir)\" 
 
@@ -90,6 +94,8 @@ OBJS = conversation.o env_hooks.o exec.o exec_common.o exec_pty.o get_pty.o \
 
 SESH_OBJS = sesh.o locale_stub.o exec_common.o
 
+CHECK_TTYNAME_OBJS = check_ttyname.o locale_stub.o ttyname.o
+
 LIBOBJDIR = $(top_builddir)/@ac_config_libobj_dir@/
 
 VERSION = @PACKAGE_VERSION@
@@ -116,6 +122,9 @@ libsudo_noexec.la: sudo_noexec.lo
 sesh: $(SESH_OBJS) @LIBINTL@ $(LT_LIBS)
 	$(LIBTOOL) --mode=link $(CC) -o $@ $(SESH_OBJS) $(LDFLAGS) $(PIE_LDFLAGS) $(SSP_LDFLAGS) @LIBINTL@ $(LIBS)
 
+check_ttyname: $(CHECK_TTYNAME_OBJS) $(top_builddir)/common/libcommon.la $(LIBOBJDIR)libreplace.la
+	$(LIBTOOL) --mode=link $(CC) -o $@ $(CHECK_TTYNAME_OBJS) $(TEST_LDFLAGS) $(PIE_LDFLAGS) $(SSP_LDFLAGS) $(TEST_LIBS)
+
 pre-install:
 
 install: install-binaries @INSTALL_NOEXEC@
@@ -146,10 +155,11 @@ uninstall:
 		$(DESTDIR)$(libexecdir)/sudo/sesh \
 		$(DESTDIR)$(noexecdir)/$(noexecfile)
 
-check:
+check: $(TEST_PROGS)
+	./check_ttyname
 
 clean:
-	-$(LIBTOOL) --mode=clean rm -f $(PROGS) *.lo *.o *.la *.a stamp-* core *.core core.*
+	-$(LIBTOOL) --mode=clean rm -f $(PROGS) $(TEST_PROGS) *.lo *.o *.la *.a stamp-* core *.core core.*
 
 mostlyclean: clean
 
@@ -164,6 +174,10 @@ realclean: distclean
 cleandir: realclean
 
 # Autogenerated dependencies, do not modify
+check_ttyname.o: $(srcdir)/regress/ttyname/check_ttyname.c \
+                 $(top_builddir)/config.h $(incdir)/missing.h \
+                 $(incdir)/alloc.h $(incdir)/error.h
+	$(CC) -c $(CPPFLAGS) $(CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(DEFS) $(srcdir)/regress/ttyname/check_ttyname.c
 conversation.o: $(srcdir)/conversation.c $(top_builddir)/config.h \
                 $(srcdir)/sudo.h $(top_builddir)/pathnames.h \
                 $(top_srcdir)/compat/stdbool.h $(incdir)/missing.h \
diff --git a/src/regress/ttyname/check_ttyname.c b/src/regress/ttyname/check_ttyname.c
new file mode 100644
index 000000000..1f2d0cc32
--- /dev/null
+++ b/src/regress/ttyname/check_ttyname.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2013 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <stdio.h>
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# ifdef HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif /* STDC_HEADERS */
+#ifdef HAVE_STRING_H
+# if defined(HAVE_MEMORY_H) && !defined(STDC_HEADERS)
+#  include <memory.h>
+# endif
+# include <string.h>
+#endif /* HAVE_STRING_H */
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif /* HAVE_STRINGS_H */
+#include <unistd.h>
+#include <errno.h>
+
+#include "missing.h"
+#include "alloc.h"
+#include "error.h"
+
+__dso_public int main(int argc, char *argv[]);
+
+extern char *get_process_ttyname(void);
+
+int
+main(int argc, char *argv[])
+{
+    char *tty_libc, *tty_sudo;
+    int rval = 0;
+
+#if !defined(HAVE_GETPROGNAME) && !defined(HAVE___PROGNAME)
+    setprogname(argc > 0 ? argv[0] : "check_ttyname");
+#endif
+
+    /* Lookup tty name via libc. */
+    if ((tty_libc = ttyname(STDIN_FILENO)) == NULL ||
+	(tty_libc = ttyname(STDOUT_FILENO)) == NULL ||
+	(tty_libc = ttyname(STDERR_FILENO)) == NULL)
+	tty_libc = "none";
+    tty_libc = estrdup(tty_libc);
+
+    /* Lookup tty name via sudo (using kernel info if possible). */
+    if ((tty_sudo = get_process_ttyname()) == NULL)
+	tty_sudo = estrdup("none");
+
+    if (strcmp(tty_libc, tty_sudo) == 0) {
+	printf("%s: OK (%s)\n", getprogname(), tty_sudo);
+    } else {
+	printf("%s: FAIL %s (sudo) vs. %s (libc)\n", getprogname(),
+	    tty_sudo, tty_libc);
+	rval = 1;
+    }
+
+    efree(tty_libc);
+    efree(tty_sudo);
+    exit(rval);
+}