diff --git a/include/mruby/numeric.h b/include/mruby/numeric.h
index aec46413c..99b642172 100644
--- a/include/mruby/numeric.h
+++ b/include/mruby/numeric.h
@@ -30,9 +30,13 @@ MRB_BEGIN_DECL
 #endif
 #endif
 
-MRB_API mrb_value mrb_num_plus(mrb_state *mrb, mrb_value x, mrb_value y);
-MRB_API mrb_value mrb_num_minus(mrb_state *mrb, mrb_value x, mrb_value y);
+/* utility functions */
+MRB_API mrb_value mrb_num_add(mrb_state *mrb, mrb_value x, mrb_value y);
+MRB_API mrb_value mrb_num_sub(mrb_state *mrb, mrb_value x, mrb_value y);
 MRB_API mrb_value mrb_num_mul(mrb_state *mrb, mrb_value x, mrb_value y);
+/* obsolete old names */
+#define mrb_num_plus(mrb, x, y) mrb_num_add(mrb, x, y)
+#define mrb_num_minus(mrb, x, y) mrb_num_sub(mrb, x, y)
 
 MRB_API mrb_value mrb_integer_to_str(mrb_state *mrb, mrb_value x, mrb_int base);
 MRB_API char *mrb_int_to_cstr(char *buf, size_t len, mrb_int n, mrb_int base);
diff --git a/src/numops.c b/src/numops.c
index 7973cfd02..8ea1cccc2 100644
--- a/src/numops.c
+++ b/src/numops.c
@@ -23,7 +23,7 @@ mrb_value mrb_rational_sub(mrb_state *mrb, mrb_value x, mrb_value y);
 mrb_value mrb_rational_mul(mrb_state *mrb, mrb_value x, mrb_value y);
 
 MRB_API mrb_value
-mrb_num_plus(mrb_state *mrb, mrb_value x, mrb_value y)
+mrb_num_add(mrb_state *mrb, mrb_value x, mrb_value y)
 {
   if (mrb_integer_p(x)) {
     return mrb_int_add(mrb, x, y);
@@ -47,7 +47,7 @@ mrb_num_plus(mrb_state *mrb, mrb_value x, mrb_value y)
 }
 
 MRB_API mrb_value
-mrb_num_minus(mrb_state *mrb, mrb_value x, mrb_value y)
+mrb_num_sub(mrb_state *mrb, mrb_value x, mrb_value y)
 {
   if (mrb_integer_p(x)) {
     return mrb_int_sub(mrb, x, y);