diff --git a/libc/tzcode/difftime.c b/libc/tzcode/difftime.c
index ba2fd03..ff78f03 100644
--- a/libc/tzcode/difftime.c
+++ b/libc/tzcode/difftime.c
@@ -1,3 +1,5 @@
+/* Return the difference between two timestamps.  */
+
 /*
 ** This file is in the public domain, so clarified as of
 ** 1996-06-05 by Arthur David Olson.
@@ -14,14 +16,14 @@
   return -x;
 }
 
-double ATTRIBUTE_CONST
+double
 difftime(time_t time1, time_t time0)
 {
 	/*
 	** If double is large enough, simply convert and subtract
 	** (assuming that the larger type has more precision).
 	*/
-	if (sizeof (time_t) < sizeof (double)) {
+	if (sizeof(time_t) < sizeof(double)) {
 	  double t1 = time1, t0 = time0;
 	  return t1 - t0;
 	}
@@ -34,7 +36,7 @@
 	  return time0 <= time1 ? time1 - time0 : dminus(time0 - time1);
 
 	/* Use uintmax_t if wide enough.  */
-	if (sizeof (time_t) <= sizeof (uintmax_t)) {
+	if (sizeof(time_t) <= sizeof(uintmax_t)) {
 	  uintmax_t t1 = time1, t0 = time0;
 	  return time0 <= time1 ? t1 - t0 : dminus(t0 - t1);
 	}