diff --git a/std/builtin.zig b/std/builtin.zig
index 0a712c7755..e2363cef18 100644
--- a/std/builtin.zig
+++ b/std/builtin.zig
@@ -3,7 +3,7 @@
 
 #debug_safety(false)
 export fn memset(dest: &u8, c: u8, n: isize) -> &u8 {
-    var index : @typeof(n) = 0;
+    var index: isize = 0;
     while (index != n) {
         dest[index] = c;
         index += 1;
@@ -13,7 +13,7 @@ export fn memset(dest: &u8, c: u8, n: isize) -> &u8 {
 
 #debug_safety(false)
 export fn memcpy(noalias dest: &u8, noalias src: &const u8, n: isize) -> &u8 {
-    var index : @typeof(n) = 0;
+    var index: isize = 0;
     while (index != n) {
         dest[index] = src[index];
         index += 1;