diff --git a/mrbgems/mruby-bigint/core/bigint.c b/mrbgems/mruby-bigint/core/bigint.c
index 437d5fc6c..c52f6f660 100644
--- a/mrbgems/mruby-bigint/core/bigint.c
+++ b/mrbgems/mruby-bigint/core/bigint.c
@@ -1327,6 +1327,10 @@ mrb_bint_sub(mrb_state *mrb, mrb_value x, mrb_value y)
 mrb_value
 mrb_bint_mul(mrb_state *mrb, mrb_value x, mrb_value y)
 {
+  if (mrb_integer_p(y)) {
+    if (mrb_integer(y) == 0) return mrb_fixnum_value(0);
+    if (mrb_integer(y) == 1) return bint_norm(mrb, RBIGINT(x));
+  }
 #ifndef MRB_NO_FLOAT
   if (mrb_float_p(y)) {
     mrb_float v1 = mrb_bint_as_float(mrb, x);
@@ -1345,6 +1349,10 @@ mrb_bint_mul(mrb_state *mrb, mrb_value x, mrb_value y)
 mrb_value
 mrb_bint_div(mrb_state *mrb, mrb_value x, mrb_value y)
 {
+  if (mrb_integer_p(y)) {
+    if (mrb_integer(y) == 0) mrb_int_zerodiv(mrb);
+    if (mrb_integer(y) == 1) return bint_norm(mrb, RBIGINT(x));
+  }
 #ifndef MRB_NO_FLOAT
   if (mrb_float_p(y)) {
     mrb_float v1 = mrb_bint_as_float(mrb, x);
@@ -1352,9 +1360,6 @@ mrb_bint_div(mrb_state *mrb, mrb_value x, mrb_value y)
     return mrb_float_value(mrb,v1*v2);
   }
 #endif
-  if (mrb_integer_p(y) && mrb_integer(y) == 0) {
-    mrb_int_zerodiv(mrb);
-  }
   y = mrb_as_bint(mrb, y);
   struct RBigint *b = RBIGINT(x);
   struct RBigint *b2 = RBIGINT(y);