diff --git a/user/src/com/google/gwt/rpc/server/CommandSerializationUtil.java b/user/src/com/google/gwt/rpc/server/CommandSerializationUtil.java
index 9e68812..5a88036 100644
--- a/user/src/com/google/gwt/rpc/server/CommandSerializationUtil.java
+++ b/user/src/com/google/gwt/rpc/server/CommandSerializationUtil.java
@@ -72,7 +72,9 @@
     BOOL {
       @Override
       public boolean canSet(Class<?> clazz) {
-        return Boolean.class.isAssignableFrom(clazz);
+        return Boolean.class.isAssignableFrom(clazz)
+            || Number.class.isAssignableFrom(clazz)
+            || String.class.isAssignableFrom(clazz);
       }
 
       @Override