diff --git a/README.md b/README.md
index bbd6784..4299ffc 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@ if ( await bigintCryptoUtils.isProbablyPrime(prime) )
     // code if is prime
 
 // Get a cryptographically secure random number between 1 and 2**256 bits.
-const rnd = bigintCryptoUtils.randBetween(BigInt(2)**256);
+const rnd = bigintCryptoUtils.randBetween(BigInt(2)**BigInt(256));
 
 ```
 
@@ -73,7 +73,7 @@ From a browser, you can just load the module in a html page as:
       alert(p.toString() + '\nIs prime?\n' + isPrime);
 
       // Get a cryptographically secure random number between 1 and 2**256 bits.
-      const rnd = await bigintCryptoUtils.randBetween(BigInt(2)**256);
+      const rnd = await bigintCryptoUtils.randBetween(BigInt(2)**BigInt(256));
       alert(rnd);
     })();
   </script>