_DATE_FMT does not always accompany CODESET.
diff --git a/Modules/_localemodule.c b/Modules/_localemodule.c
index 04cd873..3f11054 100644
--- a/Modules/_localemodule.c
+++ b/Modules/_localemodule.c
@@ -555,6 +555,9 @@
     ADDINT(ALT_DIGITS);
     ADDINT(YESEXPR);
     ADDINT(NOEXPR);
+#endif
+#ifdef _DATE_FMT
+    /* This is not available in all glibc versions that have CODESET. */
     ADDINT(_DATE_FMT);
 #endif
 #endif /* HAVE_LANGINFO_H */