diff --git a/ndn-cpp/c/encoding/BinaryXMLDecoder.c b/ndn-cpp/c/encoding/BinaryXMLDecoder.c
index b687357..b27e8bc 100644
--- a/ndn-cpp/c/encoding/BinaryXMLDecoder.c
+++ b/ndn-cpp/c/encoding/BinaryXMLDecoder.c
@@ -247,6 +247,38 @@
   return 0;
 }
 
+ndn_Error ndn_BinaryXMLDecoder_readTimeMillisecondsDTagElement
+  (struct ndn_BinaryXMLDecoder *self, unsigned int expectedTag, double *value)
+{
+  ndn_Error error;
+  unsigned char *bytes;
+  unsigned int bytesLength;
+  if (error = ndn_BinaryXMLDecoder_readBinaryDTagElement(self, expectedTag, 0, &bytes, &bytesLength))
+    return error;
+    
+  *value = 1000.0 * ndn_BinaryXMLDecoder_unsignedBigEndianToDouble(bytes, bytesLength) / 4096.0;
+  return 0;  
+}
+
+ndn_Error ndn_BinaryXMLDecoder_readOptionalTimeMillisecondsDTagElement
+  (struct ndn_BinaryXMLDecoder *self, unsigned int expectedTag, double *value)
+{
+  int gotExpectedTag;
+  ndn_Error error;
+  if (error = ndn_BinaryXMLDecoder_peekDTag(self, expectedTag, &gotExpectedTag))
+    return error;
+    
+  if (!gotExpectedTag) {
+    *value = -1.0;
+    return 0;
+  }
+
+  if (error = ndn_BinaryXMLDecoder_readTimeMillisecondsDTagElement(self, expectedTag, value))
+    return error;
+  
+  return 0;
+}
+
 double ndn_BinaryXMLDecoder_unsignedBigEndianToDouble(unsigned char *bytes, unsigned int bytesLength) 
 {
   double result = 0.0;
diff --git a/ndn-cpp/c/encoding/BinaryXMLDecoder.h b/ndn-cpp/c/encoding/BinaryXMLDecoder.h
index d157ca7..fb8afe1 100644
--- a/ndn-cpp/c/encoding/BinaryXMLDecoder.h
+++ b/ndn-cpp/c/encoding/BinaryXMLDecoder.h
@@ -132,6 +132,29 @@
   (struct ndn_BinaryXMLDecoder *self, unsigned int expectedTag, int *value);
 
 /**
+ * Decode the header from self's input starting at offset, expecting the type to be DTAG and the value to be expectedTag.
+ * Then read one item, parse it as an unsigned big endian integer in 4096 ticks per second, and convert it to milliseconds.
+ * Finally, read the element close.  Update offset.
+ * @param self pointer to the ndn_BinaryXMLDecoder struct
+ * @param expectedTag the expected value for DTAG
+ * @param value output the number of milliseconds
+ * @return 0 for success, else an error code, including an error if not the expected tag
+ */
+ndn_Error ndn_BinaryXMLDecoder_readTimeMillisecondsDTagElement
+  (struct ndn_BinaryXMLDecoder *self, unsigned int expectedTag, double *value);
+
+/**
+ * Peek at the next element, and if it has the expectedTag then call ndn_BinaryXMLDecoder_readTimeMillisecondsDTagElement.
+ * Otherwise, set value to -1.0 .
+ * @param self pointer to the ndn_BinaryXMLDecoder struct
+ * @param expectedTag the expected value for DTAG
+ * @param value output the number of milliseconds, or -1.0 if the next element doesn't have expectedTag.
+ * @return 0 for success, else an error code
+ */
+ndn_Error ndn_BinaryXMLDecoder_readOptionalTimeMillisecondsDTagElement
+  (struct ndn_BinaryXMLDecoder *self, unsigned int expectedTag, double *value);
+
+/**
  * Interpret the bytes as an unsigned big endian integer and convert to a double. Don't check for overflow.
  * We use a double because it is large enough to represent NDN time (4096 ticks per second since 1970).
  * @param bytes pointer to the array of bytes
diff --git a/ndn-cpp/c/encoding/BinaryXMLInterest.c b/ndn-cpp/c/encoding/BinaryXMLInterest.c
index 2ba6e66..337ca0f 100644
--- a/ndn-cpp/c/encoding/BinaryXMLInterest.c
+++ b/ndn-cpp/c/encoding/BinaryXMLInterest.c
@@ -216,20 +216,9 @@
       (decoder, ndn_BinaryXML_DTag_Scope, &interest->scope))
     return error;
   
-  if (error = ndn_BinaryXMLDecoder_peekDTag(decoder, ndn_BinaryXML_DTag_InterestLifetime, &gotExpectedTag))
+  if (error= ndn_BinaryXMLDecoder_readOptionalTimeMillisecondsDTagElement
+      (decoder, ndn_BinaryXML_DTag_InterestLifetime, &interest->interestLifetimeMilliseconds))
     return error;
-  if (gotExpectedTag) {
-    unsigned char *interestLifetime;
-    unsigned int interestLifetimeLength;
-    if (error = ndn_BinaryXMLDecoder_readBinaryDTagElement
-        (decoder, ndn_BinaryXML_DTag_InterestLifetime, 0, &interestLifetime, &interestLifetimeLength))
-      return error;
-    
-    interest->interestLifetimeMilliseconds = 1000.0 * 
-      ndn_BinaryXMLDecoder_unsignedBigEndianToDouble(interestLifetime, interestLifetimeLength) / 4096.0;
-  }
-  else
-    interest->interestLifetimeMilliseconds = -1.0;
   
   if (error = ndn_BinaryXMLDecoder_readOptionalBinaryDTagElement
       (decoder, ndn_BinaryXML_DTag_Nonce, 0, &interest->nonce, &interest->nonceLength))