diff --git a/server/include/utils.h b/server/include/utils.h
index 4aa77b72d..86730efa8 100644
--- a/server/include/utils.h
+++ b/server/include/utils.h
@@ -101,6 +101,10 @@ char * strcatf(char **dest, const char *fmt, ...)
 char * vstrcatf(char **dest, const char *fmt, va_list va)
 	__attribute__ ((format(printf, 2, 0)));
 
+/** Format a struct timespec date similar to strftime() */
+int strftimespec(char *s, size_t max, const char *format, struct timespec *ts)
+	__attribute__ ((format(strftime, 3, 0)));
+
 /** Convert integer to cpu_set_t.
  *
  * @param set A cpu bitmask
@@ -129,10 +133,6 @@ int version_compare(struct version *a, struct version *b);
 /** Parse a dotted version string. */
 int version_parse(const char *s, struct version *v);
 
-/** Format a struct timespec date similar to strftime() */
-int strftimespec(char *s, uint max, const char *format, struct timespec *ts)
-	__attribute__ ((format(strftime, 3, 0)));
-
 /** Check assertion and exit if failed. */
 #define assert(exp) do { \
 	if (!EXPECT(exp, 0)) \
diff --git a/server/src/ngsi.c b/server/src/ngsi.c
index 8a9ec3b46..db0445b69 100644
--- a/server/src/ngsi.c
+++ b/server/src/ngsi.c
@@ -38,15 +38,9 @@ static json_t * json_uuid()
 
 static json_t * json_date(struct timespec *ts)
 {
-	struct timespec tsp;
-	if (!ts) {
-		clock_gettime(CLOCK_REALTIME, &tsp);
-		ts = &tsp;
-	}
-	
 	// Example: 2015-09-21T11:42:25+02:00
 	char date[64];
-	strftimespec(date, sizeof(date), "%FT%T%z", ts);
+	strftimespec(date, sizeof(date), "%FT%T.%u%z", ts);
 	
 	return json_string(date);
 }
@@ -193,10 +187,10 @@ void ngsi_prepare_context(struct node *n, config_setting_t *mapping)
 			"type", "integer",
 			"value", j
 		));
-		json_array_append(metadatas, json_pack("{ s: s, s: s, s: o }",
+		json_array_append(metadatas, json_pack("{ s: s, s: s, s: s }",
 			"name", "timestamp",
 			"type", "date",
-			"value", json_date(NULL)
+			"value", ""
 		));		
 
 		if (i->structure == NGSI_CHILDREN) {
diff --git a/server/src/utils.c b/server/src/utils.c
index aab070f58..d0fe310b2 100644
--- a/server/src/utils.c
+++ b/server/src/utils.c
@@ -31,14 +31,33 @@ int version_compare(struct version *a, struct version *b) {
 	return major ? major : minor;
 }
 
-int strftimespec(char *s, uint max, const char *format, struct timespec *ts)
+int strftimespec(char *dst, size_t max, const char *fmt, struct timespec *ts)
 {
-	struct tm t;
+	int s, d;
+	char fmt2[64], dst2[64];
 
-	if (localtime_r(&(ts->tv_sec), &t) == NULL)
-	    return -1;
+	for (s=0, d=0; fmt[s] && d < 64;) {
+		char c = fmt2[d++] = fmt[s++];
+		if (c == '%') {
+			char n = fmt[s];
+			if (n == 'u') {
+				fmt2[d++] = '0';
+				fmt2[d++] = '3';
+			}
+			else
+				fmt2[d++] = '%';
+		}
+	}
+	
+	/* Print sub-second part to format string */
+	snprintf(dst2, sizeof(dst2), fmt2, ts->tv_nsec / 1000000);
 
-	return strftime(s, max, format, &t);
+	/* Print timestamp */
+	struct tm tm;
+	if (localtime_r(&(ts->tv_sec), &tm) == NULL)
+		return -1;
+
+	return strftime(dst, max, dst2, &tm);
 }
 
 double box_muller(float m, float s)