diff --git a/src/main/java/com/googlesource/gerrit/plugins/hooks/HookExecutor.java b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookExecutor.java
index 5409227..4a5f6bb 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/hooks/HookExecutor.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookExecutor.java
@@ -22,7 +22,7 @@
       new UncaughtExceptionHandler() {
         @Override
         public void uncaughtException(Thread t, Throwable e) {
-          log.error("HookExecutor thread " + t.getName() + " threw exception", e);
+          log.error("HookExecutor thread {} threw exception", t.getName(), e);
         }
       };
 
diff --git a/src/main/java/com/googlesource/gerrit/plugins/hooks/HookTask.java b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookTask.java
index 20bb088..a0b05cf 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/hooks/HookTask.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookTask.java
@@ -115,17 +115,17 @@
       args.metrics.timeout(name);
     } catch (Throwable err) {
       args.metrics.error(name);
-      log.error("Error running hook " + hook.toAbsolutePath(), err);
+      log.error("Error running hook {}", hook.toAbsolutePath(), err);
     }
 
     if (result != null && log.isDebugEnabled()) {
-      log.debug(String.format("hook[%s] exitValue: %d", name, result.getExitValue()));
+      log.debug("hook[{}] exitValue: {}", name, result.getExitValue());
 
       BufferedReader br = new BufferedReader(new StringReader(result.getOutput()));
       try {
         String line;
         while ((line = br.readLine()) != null) {
-          log.debug(String.format("hook[%s] output: %s", name, line));
+          log.debug("hook[{}] output: {}", name, line);
         }
       } catch (IOException iox) {
         log.error("Error writing hook output", iox);