diff --git a/src/main/java/com/threerings/getdown/tools/AppletParamSigner.java b/src/main/java/com/threerings/getdown/tools/AppletParamSigner.java
index 0ff4d89..15d540d 100644
--- a/src/main/java/com/threerings/getdown/tools/AppletParamSigner.java
+++ b/src/main/java/com/threerings/getdown/tools/AppletParamSigner.java
@@ -14,6 +14,8 @@ import java.security.Signature;
 import com.threerings.getdown.data.Digest;
 import com.threerings.getdown.util.Base64;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 /**
  * Produces a signed hash of the appbase, appname, and image path to ensure that signed copies of
  * Getdown are not hijacked to run malicious code.
@@ -45,7 +47,7 @@ public class AppletParamSigner
             PrivateKey key = (PrivateKey)store.getKey(alias, keypass.toCharArray());
             Signature sig = Signature.getInstance(Digest.sigAlgorithm(Digest.VERSION));
             sig.initSign(key);
-            sig.update(params.getBytes());
+            sig.update(params.getBytes(UTF_8));
             String signed = Base64.encodeToString(sig.sign(), Base64.DEFAULT);
             System.out.println("<param name=\"appbase\" value=\"" + appbase + "\" />");
             System.out.println("<param name=\"appname\" value=\"" + appname + "\" />");
diff --git a/src/main/java/com/threerings/getdown/util/Base64.java b/src/main/java/com/threerings/getdown/util/Base64.java
index ee3aa42..e00a991 100644
--- a/src/main/java/com/threerings/getdown/util/Base64.java
+++ b/src/main/java/com/threerings/getdown/util/Base64.java
@@ -107,7 +107,7 @@ public class Base64 {
      * if any are present, there must be the correct number of them.
      *
      * @param str    the input String to decode, which is converted to
-     *               bytes using the default charset
+     *               bytes using ASCII
      * @param flags  controls certain features of the decoded output.
      *               Pass {@code DEFAULT} to decode standard Base64.
      *
@@ -115,7 +115,7 @@ public class Base64 {
      * incorrect padding
      */
     public static byte[] decode(String str, int flags) {
-        return decode(str.getBytes(), flags);
+        return decode(str.getBytes(US_ASCII), flags);
     }
 
     /**