diff --git a/classpath/java/lang/StringBuffer.java b/classpath/java/lang/StringBuffer.java
index beef64b68e..45528396fe 100644
--- a/classpath/java/lang/StringBuffer.java
+++ b/classpath/java/lang/StringBuffer.java
@@ -30,6 +30,16 @@ public class StringBuffer implements CharSequence {
     return this;
   }
 
+  public synchronized StringBuffer append(CharSequence s) {
+    sb.append(s);
+    return this;
+  }
+
+  public synchronized StringBuffer append(StringBuffer s) {
+    sb.append(s);
+    return this;
+  }
+
   public synchronized StringBuffer append(Object o) {
     sb.append(o);
     return this;
diff --git a/classpath/java/lang/StringBuilder.java b/classpath/java/lang/StringBuilder.java
index 0a322a5e69..d4e98571d7 100644
--- a/classpath/java/lang/StringBuilder.java
+++ b/classpath/java/lang/StringBuilder.java
@@ -54,6 +54,10 @@ public class StringBuilder implements CharSequence, Appendable {
     }
   }
 
+  public StringBuilder append(StringBuffer sb) {
+    return append(sb.toString());
+  }
+
   public StringBuilder append(CharSequence sequence) {
     return append(sequence.toString());
   }
@@ -104,7 +108,6 @@ public class StringBuilder implements CharSequence, Appendable {
     return append(String.valueOf(v));
   }
 
-
   public char charAt(int i) {
     if (i < 0 || i >= length) {
       throw new IndexOutOfBoundsException();