diff --git a/ndn-cpp/c/Interest.h b/ndn-cpp/c/Interest.h
index 832fb96..ada7a7e 100644
--- a/ndn-cpp/c/Interest.h
+++ b/ndn-cpp/c/Interest.h
@@ -85,7 +85,7 @@
 	int childSelector;        /**< -1 for none */
 	int answerOriginKind;     /**< -1 for none */
 	int scope;                /**< -1 for none */
-	int interestLifetime;     /**< milliseconds. -1 for none */
+	double interestLifetimeMilliseconds; /**< milliseconds. -1.0 for none */
 	unsigned char *nonce;	    /**< pointer to pre-allocated buffer.  0 for none */
   unsigned int nonceLength; /**< length of nonce.  0 for none */
 };
@@ -111,7 +111,7 @@
 	self->childSelector = -1;
 	self->answerOriginKind = -1;
 	self->scope = -1;
-	self->interestLifetime = -1;
+	self->interestLifetimeMilliseconds = -1.0;
 	self->nonce = 0;
 	self->nonceLength = 0;
 }
diff --git a/ndn-cpp/c/encoding/BinaryXMLInterest.c b/ndn-cpp/c/encoding/BinaryXMLInterest.c
index 5708761..1dda876 100644
--- a/ndn-cpp/c/encoding/BinaryXMLInterest.c
+++ b/ndn-cpp/c/encoding/BinaryXMLInterest.c
@@ -155,11 +155,11 @@
       (encoder, ndn_BinaryXML_DTag_Scope, interest->scope))
     return error;
   
-  if (interest->interestLifetime >= 0) {
+  if (interest->interestLifetimeMilliseconds >= 0) {
     if (error = ndn_BinaryXMLEncoder_writeElementStartDTag(encoder, ndn_BinaryXML_DTag_InterestLifetime))
       return error;
    
-    unsigned int ticks = (unsigned int)(((double)interest->interestLifetime / 1000.0) * 4096.0);
+    unsigned int ticks = (unsigned int)((interest->interestLifetimeMilliseconds / 1000.0) * 4096.0);
     if (error = ndn_BinaryXMLEncoder_writeUnsignedIntBigEndianBlob(encoder, ticks))
       return error;
     
@@ -225,11 +225,11 @@
         (decoder, ndn_BinaryXML_DTag_InterestLifetime, 0, &interestLifetime, &interestLifetimeLength))
       return error;
     
-    interest->interestLifetime = (int)(1000.0 * 
-      (double)ndn_BinaryXMLDecoder_bigEndianToUnsignedInt(interestLifetime, interestLifetimeLength) / 4096.0);
+    interest->interestLifetimeMilliseconds = 1000.0 * 
+      (double)ndn_BinaryXMLDecoder_bigEndianToUnsignedInt(interestLifetime, interestLifetimeLength) / 4096.0;
   }
   else
-    interest->interestLifetime = -1;
+    interest->interestLifetimeMilliseconds = -1.0;
   
   if (error = ndn_BinaryXMLDecoder_readOptionalBinaryDTagElement
       (decoder, ndn_BinaryXML_DTag_Nonce, 0, &interest->nonce, &interest->nonceLength))