diff --git a/res/c64.wasm b/res/c64.wasm
index 0f9552d2..c0b80b0e 100755
Binary files a/res/c64.wasm and b/res/c64.wasm differ
diff --git a/res/zx.wasm b/res/zx.wasm
index eba51622..56e54573 100755
Binary files a/res/zx.wasm and b/res/zx.wasm differ
diff --git a/src/machine/c64.ts b/src/machine/c64.ts
index 4cb0d2f1..568de4ae 100644
--- a/src/machine/c64.ts
+++ b/src/machine/c64.ts
@@ -52,9 +52,9 @@ export class C64_WASMMachine extends BaseWASMMachine implements Machine, Probeab
         var cmd = "SYS "+this.prgstart+"\r";
         for (var i=0; i<cmd.length; i++) {
           var key = cmd.charCodeAt(i);
-          this.exports.machine_exec(this.sys, 10000);
+          this.exports.machine_exec(this.sys, 20000);
           this.exports.machine_key_down(this.sys, key);
-          this.exports.machine_exec(this.sys, 10000);
+          this.exports.machine_exec(this.sys, 20000);
           this.exports.machine_key_up(this.sys, key);
         }
         // advance clock until program starts