diff --git a/src/main/java/com/googlesource/gerrit/plugins/serviceuser/CreateServiceUserCommand.java b/src/main/java/com/googlesource/gerrit/plugins/serviceuser/CreateServiceUserCommand.java
index a73859c..bebd520 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/serviceuser/CreateServiceUserCommand.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/serviceuser/CreateServiceUserCommand.java
@@ -14,6 +14,8 @@
 
 package com.googlesource.gerrit.plugins.serviceuser;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import com.google.gerrit.extensions.annotations.RequiresCapability;
 import com.google.gerrit.extensions.restapi.IdString;
 import com.google.gerrit.extensions.restapi.RestApiException;
@@ -26,7 +28,6 @@
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
-import java.io.UnsupportedEncodingException;
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.kohsuke.args4j.Argument;
 import org.kohsuke.args4j.Option;
@@ -62,17 +63,18 @@
     }
   }
 
-  private String readSshKey() throws UnsupportedEncodingException, IOException {
+  private String readSshKey() throws IOException {
     if (sshKey == null) {
       return null;
     }
     if ("-".equals(sshKey)) {
-      sshKey = "";
-      BufferedReader br = new BufferedReader(new InputStreamReader(in, "UTF-8"));
+      StringBuilder key = new StringBuilder();
+      BufferedReader br = new BufferedReader(new InputStreamReader(in, UTF_8));
       String line;
       while ((line = br.readLine()) != null) {
-        sshKey += line + "\n";
+        key.append(line).append("\n");
       }
+      sshKey = key.toString();
     }
     return sshKey;
   }
diff --git a/src/main/java/com/googlesource/gerrit/plugins/serviceuser/CreateServiceUserNotes.java b/src/main/java/com/googlesource/gerrit/plugins/serviceuser/CreateServiceUserNotes.java
index 62c01d1..c0e4c20 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/serviceuser/CreateServiceUserNotes.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/serviceuser/CreateServiceUserNotes.java
@@ -16,6 +16,7 @@
 
 import static com.googlesource.gerrit.plugins.serviceuser.CreateServiceUser.KEY_CREATED_BY;
 import static com.googlesource.gerrit.plugins.serviceuser.CreateServiceUser.KEY_OWNER;
+import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.eclipse.jgit.lib.Constants.OBJ_COMMIT;
 
 import com.google.gerrit.extensions.common.AccountInfo;
@@ -157,7 +158,7 @@
   private ObjectId createNoteContent(String branch, ServiceUserInfo serviceUser)
       throws IOException, OrmException, MethodNotAllowedException, PermissionBackendException {
     return getInserter()
-        .insert(Constants.OBJ_BLOB, createServiceUserNote(branch, serviceUser).getBytes("UTF-8"));
+        .insert(Constants.OBJ_BLOB, createServiceUserNote(branch, serviceUser).getBytes(UTF_8));
   }
 
   private String createServiceUserNote(String branch, ServiceUserInfo serviceUser)