diff --git a/logback-core/src/main/java/ch/qos/logback/core/rolling/FixedWindowRollingPolicy.java b/logback-core/src/main/java/ch/qos/logback/core/rolling/FixedWindowRollingPolicy.java
index 914d7450eb..7573a888f6 100644
--- a/logback-core/src/main/java/ch/qos/logback/core/rolling/FixedWindowRollingPolicy.java
+++ b/logback-core/src/main/java/ch/qos/logback/core/rolling/FixedWindowRollingPolicy.java
@@ -40,9 +40,9 @@ public class FixedWindowRollingPolicy extends RollingPolicyBase {
   public static final String ZIP_ENTRY_DATE_PATTERN = "yyyy-MM-dd_HHmm";
 
   /**
-   * It's almost always a bad idea to have a large window size, say over 12.
+   * It's almost always a bad idea to have a large window size, say over 20.
    */
-  private static int MAX_WINDOW_SIZE = 12;
+  private static int MAX_WINDOW_SIZE = 20;
 
   public FixedWindowRollingPolicy() {
     minIndex = 1;
@@ -80,9 +80,10 @@ public void start() {
       maxIndex = minIndex;
     }
 
-    if ((maxIndex - minIndex) > MAX_WINDOW_SIZE) {
+    final int maxWindowSize = getMaxWindowSize();
+    if ((maxIndex - minIndex) > maxWindowSize) {
       addWarn("Large window sizes are not allowed.");
-      maxIndex = minIndex + MAX_WINDOW_SIZE;
+      maxIndex = minIndex + maxWindowSize;
       addWarn("MaxIndex reduced to " + maxIndex);
     }
 
@@ -103,6 +104,15 @@ public void start() {
     super.start();
   }
 
+  /**
+   * Subclasses can override this method to increase the max window size, if required.  This is to
+   * address LOGBACK-266.
+   * @return
+   */
+  protected int getMaxWindowSize() {
+    return MAX_WINDOW_SIZE;
+  }
+
   private String transformFileNamePatternFromInt2Date(String fileNamePatternStr) {
     String slashified = FileFilterUtil.slashify(fileNamePatternStr);
     String stemOfFileNamePattern = FileFilterUtil.afterLastSlash(slashified);