diff --git a/src/hash.c b/src/hash.c
index b2869aef5..365019352 100644
--- a/src/hash.c
+++ b/src/hash.c
@@ -382,7 +382,7 @@ obj_eql(mrb_state *mrb, mrb_value a, mrb_value b, struct RHash *h)
   }
 }
 
-static mrb_bool
+static inline mrb_bool
 entry_deleted_p(const hash_entry* entry)
 {
   return mrb_undef_p(entry->key);
diff --git a/src/vm.c b/src/vm.c
index 741bd2175..b4639e43e 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -609,7 +609,7 @@ funcall_args_capture(mrb_state *mrb, int stoff, mrb_int argc, const mrb_value *a
   }
 }
 
-static mrb_value
+static inline mrb_value
 ensure_block(mrb_state *mrb, mrb_value blk)
 {
   if (!mrb_nil_p(blk) && !mrb_proc_p(blk)) {