src/session.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/session.c b/src/session.c
index 2d77b05..79809cc 100644
--- a/src/session.c
+++ b/src/session.c
@@ -68,6 +68,8 @@
 #undef libssh2_usec_t
 #endif
 
+#define DIFFTIME(_b,_a) ((double)((_b) - (_a)))
+
 /* libssh2_default_alloc
  */
 static
@@ -628,7 +630,7 @@ int _libssh2_wait_socket(LIBSSH2_SESSION *session, time_t start_time)
         (seconds_to_next == 0 ||
          ms_to_next > session->api_timeout)) {
         time_t now = time(NULL);
-        elapsed_ms = (long)(1000*difftime(now, start_time));
+        elapsed_ms = (long)(1000*DIFFTIME(now, start_time));
         if(elapsed_ms > session->api_timeout) {
             return _libssh2_error(session, LIBSSH2_ERROR_TIMEOUT,
                                   "API timeout expired");