diff --git a/jetty-util/src/main/java/org/eclipse/jetty/util/log/JavaUtilLog.java b/jetty-util/src/main/java/org/eclipse/jetty/util/log/JavaUtilLog.java
index 9a460d8395c..464ed52d1df 100644
--- a/jetty-util/src/main/java/org/eclipse/jetty/util/log/JavaUtilLog.java
+++ b/jetty-util/src/main/java/org/eclipse/jetty/util/log/JavaUtilLog.java
@@ -126,8 +126,11 @@ public class JavaUtilLog implements Logger
             if (bracesIndex < 0)
             {
                 builder.append(msg.substring(start));
-                builder.append(" ");
-                builder.append(String.valueOf(arg));
+                if (arg != null)
+                {
+                    builder.append(" ");
+                    builder.append(arg);
+                }
                 start = msg.length();
             }
             else
diff --git a/jetty-util/src/main/java/org/eclipse/jetty/util/log/StdErrLog.java b/jetty-util/src/main/java/org/eclipse/jetty/util/log/StdErrLog.java
index ef901dcbee4..7608dd91641 100644
--- a/jetty-util/src/main/java/org/eclipse/jetty/util/log/StdErrLog.java
+++ b/jetty-util/src/main/java/org/eclipse/jetty/util/log/StdErrLog.java
@@ -197,8 +197,11 @@ public class StdErrLog implements Logger
             if (bracesIndex < 0)
             {
                 escape(builder, msg.substring(start));
-                builder.append(" ");
-                builder.append(String.valueOf(arg));
+                if (arg != null)
+                {
+                    builder.append(" ");
+                    builder.append(arg);
+                }
                 start = msg.length();
             }
             else