diff --git a/src/gc.c b/src/gc.c
index 83f3f9c0d..825d54600 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -245,8 +245,7 @@ mrb_calloc(mrb_state *mrb, size_t nelem, size_t len)
 
   if (nelem > 0 && len > 0 &&
       nelem <= SIZE_MAX / len) {
-    size_t size;
-    size = nelem * len;
+    size_t size = nelem * len;
     p = mrb_malloc(mrb, size);
 
     memset(p, 0, size);