diff --git a/ndn-cpp/c/util/time.h b/ndn-cpp/c/util/time.h
index adcb0b4..454216e 100644
--- a/ndn-cpp/c/util/time.h
+++ b/ndn-cpp/c/util/time.h
@@ -20,6 +20,14 @@
 ndn_MillisecondsSince1970 
 ndn_getNowMilliseconds();
 
+/**
+ * Convert the time from milliseconds to ISO time, for example "20131018T184138.423355".
+ * @param milliseconds The time in milliseconds since 1/1/1970, including fractions of a millisecond.
+ * @param isoString A buffer of at least 23 bytes to receive the null-terminated ISO time string.
+ */
+void
+ndn_toIsoString(ndn_MillisecondsSince1970 time, char *isoString);
+
 #ifdef  __cplusplus
 }
 #endif