diff --git a/opt/bignum.c b/opt/bignum.c
index 9af36997..2cd42bb0 100644
--- a/opt/bignum.c
+++ b/opt/bignum.c
@@ -631,7 +631,7 @@ sexp sexp_div (sexp ctx, sexp a, sexp b) {
     r = sexp_make_flonum(ctx, sexp_fixnum_to_double(a)/sexp_bignum_to_double(b));
     break;
   case SEXP_NUM_FLO_FIX:
-    r = sexp_make_flonum(ctx, sexp_fixnum_to_double(b)/sexp_flonum_value(a));
+    r = sexp_make_flonum(ctx, sexp_flonum_value(a)/sexp_fixnum_to_double(b));
     break;
   case SEXP_NUM_FLO_FLO:
     r = sexp_fp_div(ctx, a, b);