diff --git a/ndn-cpp/c/data.h b/ndn-cpp/c/data.h
index 8d14e05..68ed6ed 100644
--- a/ndn-cpp/c/data.h
+++ b/ndn-cpp/c/data.h
@@ -46,10 +46,10 @@
  * An ndn_MetaInfo struct holds the meta info which is signed inside the data packet.
  */
 struct ndn_MetaInfo {
-  double timestampMilliseconds;    /**< milliseconds since 1/1/1970. -1 for none */
-  ndn_ContentType type;            /**< default is ndn_ContentType_DATA. -1 for none */
-  int freshnessSeconds;            /**< -1 for none */
-  struct ndn_NameComponent finalBlockID;  /**< has a pointer to a pre-allocated buffer.  0 for none */
+  ndn_MillisecondsSince1970 timestampMilliseconds; /**< milliseconds since 1/1/1970. -1 for none */
+  ndn_ContentType type;                  /**< default is ndn_ContentType_DATA. -1 for none */
+  int freshnessSeconds;                  /**< -1 for none */
+  struct ndn_NameComponent finalBlockID; /**< has a pointer to a pre-allocated buffer.  0 for none */
 };
 
 /**
diff --git a/ndn-cpp/c/interest.h b/ndn-cpp/c/interest.h
index 12ca38e..438fecd 100644
--- a/ndn-cpp/c/interest.h
+++ b/ndn-cpp/c/interest.h
@@ -99,7 +99,7 @@
   int childSelector;        /**< -1 for none */
   int answerOriginKind;     /**< -1 for none */
   int scope;                /**< -1 for none */
-  double interestLifetimeMilliseconds; /**< milliseconds. -1.0 for none */
+  ndn_Milliseconds interestLifetimeMilliseconds; /**< milliseconds. -1.0 for none */
   struct ndn_Blob nonce;    /**< The blob whose value is a pointer to a pre-allocated buffer.  0 for none */
 };
 
diff --git a/ndn-cpp/c/util/time.c b/ndn-cpp/c/util/time.c
index a794047..9da0e1c 100644
--- a/ndn-cpp/c/util/time.c
+++ b/ndn-cpp/c/util/time.c
@@ -7,7 +7,7 @@
 #include <sys/time.h>
 #include "time.h"
 
-double 
+ndn_MillisecondsSince1970 
 ndn_getNowMilliseconds()
 {
   struct timeval t;
diff --git a/ndn-cpp/c/util/time.h b/ndn-cpp/c/util/time.h
index 36b4dad..adcb0b4 100644
--- a/ndn-cpp/c/util/time.h
+++ b/ndn-cpp/c/util/time.h
@@ -7,6 +7,8 @@
 #ifndef NDN_TIME_H
 #define NDN_TIME_H
 
+#include <ndn-cpp/c/common.h>
+
 #ifdef  __cplusplus
 extern "C" {
 #endif
@@ -15,7 +17,7 @@
  * Use gettimeofday to return the current time in milliseconds.
  * @return The current time in milliseconds since 1/1/1970, including fractions of a millisecond according to timeval.tv_usec.
  */
-double 
+ndn_MillisecondsSince1970 
 ndn_getNowMilliseconds();
 
 #ifdef  __cplusplus