diff --git a/include/asterisk/strings.h b/include/asterisk/strings.h
index e0e5148a3f639442e77461c1ff55a9d77697f797..508a3ba7e959af10754373ae7fe42341ee3f5450 100755
--- a/include/asterisk/strings.h
+++ b/include/asterisk/strings.h
@@ -174,6 +174,20 @@ void ast_copy_string(char *dst, const char *src, size_t size),
 */
 int ast_build_string(char **buffer, size_t *space, const char *fmt, ...) __attribute__ ((format (printf, 3, 4)));
 
+/*!
+  \brief Build a string in a buffer, designed to be called repeatedly
+  
+  This is a wrapper for snprintf, that properly handles the buffer pointer
+  and buffer space available.
+
+  \return 0 on success, non-zero on failure.
+  \param buffer current position in buffer to place string into (will be updated on return)
+  \param space remaining space in buffer (will be updated on return)
+  \param fmt printf-style format string
+  \param ap varargs list of arguments for format
+*/
+int ast_build_string_va(char **buffer, size_t *space, const char *fmt, va_list ap);
+
 /*! Make sure something is true */
 /*!
  * Determine if a string containing a boolean value is "true".
diff --git a/manager.c b/manager.c
index 059c7298d46cdd9e2e58f690f229a1ca87a96a74..5e8cac8be0c93951f5d62f832d52c23a716ccaec 100755
--- a/manager.c
+++ b/manager.c
@@ -1473,13 +1473,16 @@ static int append_event(struct mansession *s, const char *str)
 int manager_event(int category, char *event, char *fmt, ...)
 {
 	struct mansession *s;
+	char auth[80];
 	char tmp[4096];
-	char auth[256];
+	char *tmp_next = tmp;
+	size_t tmp_left = sizeof(tmp) - 2;
 	va_list ap;
 
-	authority_to_str(category, auth, sizeof(auth));
+	ast_build_string(&tmp_next, &tmp_left, "Event: %s\r\nPrivilege: %s\r\n",
+			 event, authority_to_str(category, auth, sizeof(auth)));
 	va_start(ap, fmt);
-	vsnprintf(tmp, sizeof(tmp) - 3, fmt, ap);
+	ast_build_string_va(&tmp_next, &tmp_left, fmt, ap);
 	va_end(ap);
 	strcat(tmp, "\r\n");
 
@@ -1492,11 +1495,9 @@ int manager_event(int category, char *event, char *fmt, ...)
 			continue;
 
 		ast_mutex_lock(&s->__lock);
-		ast_cli(s->fd, "Event: %s\r\n", event);
-		ast_cli(s->fd, "Privilege: %s\r\n", auth);
 		if (s->busy) {
 			append_event(s, tmp);
-		} else if (ast_carefulwrite(s->fd, tmp, strlen(tmp), 100) < 0) {
+		} else if (ast_carefulwrite(s->fd, tmp, sizeof(tmp) - tmp_left + 1, 100) < 0) {
 			ast_log(LOG_WARNING, "Disconnecting slow (or gone) manager session!\n");
 			s->dead = 1;
 			pthread_kill(s->t, SIGURG);
diff --git a/utils.c b/utils.c
index 79d73360543d1693e83aa4c84a75ec3914726f8c..fd99d581f369aaf36be084d450fa4194047b21a9 100755
--- a/utils.c
+++ b/utils.c
@@ -522,17 +522,14 @@ char *ast_strip_quoted(char *s, const char *beg_quotes, const char *end_quotes)
 	return s;
 }
 
-int ast_build_string(char **buffer, size_t *space, const char *fmt, ...)
+int ast_build_string_va(char **buffer, size_t *space, const char *fmt, va_list ap)
 {
-	va_list ap;
 	int result;
 
 	if (!buffer || !*buffer || !space || !*space)
 		return -1;
 
-	va_start(ap, fmt);
 	result = vsnprintf(*buffer, *space, fmt, ap);
-	va_end(ap);
 
 	if (result < 0)
 		return -1;
@@ -544,6 +541,18 @@ int ast_build_string(char **buffer, size_t *space, const char *fmt, ...)
 	return 0;
 }
 
+int ast_build_string(char **buffer, size_t *space, const char *fmt, ...)
+{
+	va_list ap;
+	int result;
+
+	va_start(ap, fmt);
+	result = ast_build_string_va(buffer, space, fmt, ap);
+	va_end(ap);
+
+	return result;
+}
+
 int ast_true(const char *s)
 {
 	if (!s || ast_strlen_zero(s))