diff --git a/include/mruby.h b/include/mruby.h
index d40dce6d9..bc6800e29 100644
--- a/include/mruby.h
+++ b/include/mruby.h
@@ -64,6 +64,13 @@
 #endif
 
 #include "mrbconf.h"
+
+#ifdef MRB_USE_FLOAT
+#define MRB_FLOAT_EPSILON FLT_EPSILON
+#else
+#define MRB_FLOAT_EPSILON DBL_EPSILON
+#endif
+
 #include "mruby/common.h"
 #include <mruby/value.h>
 #include <mruby/gc.h>
diff --git a/mrbgems/mruby-range-ext/src/range.c b/mrbgems/mruby-range-ext/src/range.c
index 32222a594..ccb5a9e45 100644
--- a/mrbgems/mruby-range-ext/src/range.c
+++ b/mrbgems/mruby-range-ext/src/range.c
@@ -140,7 +140,7 @@ mrb_range_size(mrb_state *mrb, mrb_value range)
   }
   if (num_p) {
     mrb_float n = end_f - beg_f;
-    mrb_float err = (fabs(beg_f) + fabs(end_f) + fabs(end_f-beg_f)) * DBL_EPSILON;
+    mrb_float err = (fabs(beg_f) + fabs(end_f) + fabs(end_f-beg_f)) * MRB_FLOAT_EPSILON;
 
     if (err>0.5) err=0.5;
     if (excl) {