diff --git a/mrbgems/mruby-time/src/time.c b/mrbgems/mruby-time/src/time.c
index 44bea5ffa..2a5e9dd6b 100644
--- a/mrbgems/mruby-time/src/time.c
+++ b/mrbgems/mruby-time/src/time.c
@@ -226,6 +226,7 @@ typedef mrb_int mrb_sec;
                     (sizeof(time_t) <= 4 ? INT32_MAX : INT64_MAX)           \
 )
 
+#ifndef MRB_NO_FLOAT
 /* return true if time_t is fit in mrb_int */
 static mrb_bool
 fixable_time_t_p(time_t v)
@@ -236,6 +237,7 @@ fixable_time_t_p(time_t v)
   if (MRB_INT_MIN > (mrb_int)v) return FALSE;
   return TRUE;
 }
+#endif
 
 static time_t
 mrb_to_time_t(mrb_state *mrb, mrb_value obj, time_t *usec)