diff --git a/lib/posixtm.h b/lib/posixtm.h
new file mode 100644
index 000000000..f2bca7943
--- /dev/null
+++ b/lib/posixtm.h
@@ -0,0 +1,11 @@
+/* POSIX Date Syntax flags.  */
+#define PDS_LEADING_YEAR 1
+#define PDS_TRAILING_YEAR 2
+#define PDS_CENTURY 4
+#define PDS_SECONDS 8
+
+time_t
+posixtime (const char *s, unsigned int syntax_bits);
+
+struct tm *
+posixtm (const char *s, unsigned int syntax_bits);