diff --git a/difftime.c b/difftime.c
new file mode 100644
index 0000000..10125d9
--- /dev/null
+++ b/difftime.c
@@ -0,0 +1,18 @@
+#ifndef lint
+#ifndef NOID
+static char	elsieid[] = "%W%";
+#endif /* !defined NOID */
+#endif /* !defined lint */
+
+/*LINTLIBRARY*/
+
+#include "time.h"
+#include "nonstd.h"
+
+double
+difftime(time1, time0)
+const time_t	time1;
+const time_t	time0;
+{
+	return time1 - time0;
+}