diff --git a/src/main/java/org/apache/commons/logging/impl/AvalonLogger.java b/src/main/java/org/apache/commons/logging/impl/AvalonLogger.java
index 58950e5..90e666c 100644
--- a/src/main/java/org/apache/commons/logging/impl/AvalonLogger.java
+++ b/src/main/java/org/apache/commons/logging/impl/AvalonLogger.java
@@ -52,7 +52,7 @@ import org.apache.commons.logging.Log;
 public class AvalonLogger implements Log {
 
     /** Ancestral Avalon logger. */
-    private static Logger defaultLogger = null;
+    private static volatile Logger defaultLogger = null;
     /** Avalon logger used to perform log. */
     private final transient Logger logger;
 
diff --git a/src/main/java/org/apache/commons/logging/impl/SimpleLog.java b/src/main/java/org/apache/commons/logging/impl/SimpleLog.java
index 263ad2d..919c4f0 100644
--- a/src/main/java/org/apache/commons/logging/impl/SimpleLog.java
+++ b/src/main/java/org/apache/commons/logging/impl/SimpleLog.java
@@ -85,19 +85,19 @@ public class SimpleLog implements Log, Serializable {
     static protected final String DEFAULT_DATE_TIME_FORMAT = "yyyy/MM/dd HH:mm:ss:SSS zzz";
 
     /** Include the instance name in the log message? */
-    static protected boolean showLogName = false;
+    static volatile protected boolean showLogName = false;
 
     /** Include the short name ( last component ) of the logger in the log
      *  message. Defaults to true - otherwise we'll be lost in a flood of
      *  messages without knowing who sends them.
      */
-    static protected boolean showShortName = true;
+    static volatile protected boolean showShortName = true;
 
     /** Include the current time in the log message */
-    static protected boolean showDateTime = false;
+    static volatile protected boolean showDateTime = false;
 
     /** The date and time format to use in the log message */
-    static protected String dateTimeFormat = DEFAULT_DATE_TIME_FORMAT;
+    static volatile protected String dateTimeFormat = DEFAULT_DATE_TIME_FORMAT;
 
     /**
      * Used to format times.
@@ -187,11 +187,11 @@ public class SimpleLog implements Log, Serializable {
     // ------------------------------------------------------------- Attributes
 
     /** The name of this simple log instance */
-    protected String logName = null;
+    protected volatile String logName = null;
     /** The current log level */
-    protected int currentLogLevel;
+    protected volatile int currentLogLevel;
     /** The short name of this simple log instance */
-    private String shortLogName = null;
+    private volatile String shortLogName = null;
 
     // ------------------------------------------------------------ Constructor