1 files changed, 8 insertions, 5 deletions

diff --git a/src/timefns.c b/src/timefns.c
index 0df7d1f4363..ba1ba10a809 100644
--- a/src/timefns.c
+++ b/src/timefns.c
@@ -774,8 +774,8 @@ ticks_hz_hz_ticks (struct ticks_hz t, Lisp_Object hz)
       if (XFIXNUM (hz) <= 0)
         invalid_hz (hz);
 
-      /* For speed, use intmax_t arithmetic if it will do.  */
-      if (FASTER_TIMEFNS && FIXNUMP (t.ticks) && FIXNUMP (t.hz))
+      /* Prefer non-bignum arithmetic to speed up common cases.  */
+      if (FASTER_TIMEFNS && FIXNUMP (t.hz))
         {
           /* Reduce T.hz and HZ by their GCD, to avoid some intmax_t
              overflows that would occur in T.ticks * HZ.  */
@@ -784,9 +784,12 @@ ticks_hz_hz_ticks (struct ticks_hz t, Lisp_Object hz)
           ithz /= d;
           ihz /= d;
 
-          intmax_t ticks;
-          if (!ckd_mul (&ticks, XFIXNUM (t.ticks), ihz))
-            return make_int (ticks / ithz - (ticks % ithz < 0));
+          if (FIXNUMP (t.ticks))
+            {
+              intmax_t ticks;
+              if (!ckd_mul (&ticks, XFIXNUM (t.ticks), ihz))
+                return make_int (ticks / ithz - (ticks % ithz < 0));
+            }
 
           t.hz = make_fixnum (ithz);
           hz = make_fixnum (ihz);