diff --git a/Misc/ACKS b/Misc/ACKS
index 8e1b6f7..2cf5e10 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -18,6 +18,7 @@
 Marc Abramowitz
 Eldar Abusalimov
 Ron Adam
+Eitan Adler
 Anton Afanasyev
 Ali Afshar
 Nitika Agarwal
diff --git a/Misc/NEWS.d/next/Build/2018-05-25-13-05-51.bpo-33648.bJ4JZH.rst b/Misc/NEWS.d/next/Build/2018-05-25-13-05-51.bpo-33648.bJ4JZH.rst
new file mode 100644
index 0000000..eaac4eb
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2018-05-25-13-05-51.bpo-33648.bJ4JZH.rst
@@ -0,0 +1,2 @@
+The --with-c-locale-warning configuration flag has been removed. It has had
+no effect for about a year.
diff --git a/configure b/configure
index d427703..21067e8 100755
--- a/configure
+++ b/configure
@@ -829,7 +829,6 @@
 with_doc_strings
 with_pymalloc
 with_c_locale_coercion
-with_c_locale_warning
 with_valgrind
 with_dtrace
 with_libm
@@ -1523,9 +1522,6 @@
   --with(out)-c-locale-coercion
                           disable/enable C locale coercion to a UTF-8 based
                           locale
-  --with(out)-c-locale-warning
-                          disable/enable locale compatibility warning in the C
-                          locale
   --with-valgrind         Enable Valgrind support
   --with(out)-dtrace      disable/enable DTrace support
   --with-libm=STRING      math library
@@ -11046,29 +11042,6 @@
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_c_locale_coercion" >&5
 $as_echo "$with_c_locale_coercion" >&6; }
 
-# Check for --with-c-locale-warning
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for --with-c-locale-warning" >&5
-$as_echo_n "checking for --with-c-locale-warning... " >&6; }
-
-# Check whether --with-c-locale-warning was given.
-if test "${with_c_locale_warning+set}" = set; then :
-  withval=$with_c_locale_warning;
-fi
-
-
-if test -z "$with_c_locale_warning"
-then
-    with_c_locale_warning="yes"
-fi
-if test "$with_c_locale_warning" != "no"
-then
-
-$as_echo "#define PY_WARN_ON_C_LOCALE 1" >>confdefs.h
-
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_c_locale_warning" >&5
-$as_echo "$with_c_locale_warning" >&6; }
-
 # Check for Valgrind support
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for --with-valgrind" >&5
 $as_echo_n "checking for --with-valgrind... " >&6; }
diff --git a/configure.ac b/configure.ac
index b98ceb2..99aca665 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3319,23 +3319,6 @@
 fi
 AC_MSG_RESULT($with_c_locale_coercion)
 
-# Check for --with-c-locale-warning
-AC_MSG_CHECKING(for --with-c-locale-warning)
-AC_ARG_WITH(c-locale-warning,
-            AS_HELP_STRING([--with(out)-c-locale-warning],
-              [disable/enable locale compatibility warning in the C locale]))
-
-if test -z "$with_c_locale_warning"
-then
-    with_c_locale_warning="yes"
-fi
-if test "$with_c_locale_warning" != "no"
-then
-    AC_DEFINE(PY_WARN_ON_C_LOCALE, 1,
-      [Define to emit a locale compatibility warning in the C locale])
-fi
-AC_MSG_RESULT($with_c_locale_warning)
-
 # Check for Valgrind support
 AC_MSG_CHECKING([for --with-valgrind])
 AC_ARG_WITH([valgrind],
diff --git a/pyconfig.h.in b/pyconfig.h.in
index 9148319..e8ad150 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -1327,9 +1327,6 @@
 /* Cipher suite string for PY_SSL_DEFAULT_CIPHERS=0 */
 #undef PY_SSL_DEFAULT_CIPHER_STRING
 
-/* Define to emit a locale compatibility warning in the C locale */
-#undef PY_WARN_ON_C_LOCALE
-
 /* Define if you want to build an interpreter with many run-time checks. */
 #undef Py_DEBUG