diff --git a/src/com/sun/jna/Library.java b/src/com/sun/jna/Library.java
index 621e4f3552..5928e79e3a 100644
--- a/src/com/sun/jna/Library.java
+++ b/src/com/sun/jna/Library.java
@@ -118,20 +118,6 @@ static class Handler implements InvocationHandler {
             }
         }
 
-        private static class FunctionNameMap implements FunctionMapper {
-            private final Map map;
-            public FunctionNameMap(Map map) {
-                this.map = new HashMap(map);
-            }
-            public String getFunctionName(NativeLibrary library, Method method) {
-                String name = method.getName();
-                if (map.containsKey(name)) {
-                    return (String)map.get(name);
-                }
-                return name;
-            }
-        }
-
         private final NativeLibrary nativeLibrary;
         private final Class interfaceClass;
         // Library invocation options
@@ -154,9 +140,8 @@ public Handler(String libname, Class interfaceClass, Map options) {
                 options.put(OPTION_CALLING_CONVENTION,
                             new Integer(callingConvention));
             }
-            if (!options.containsKey(OPTION_FUNCTION_MAPPER)) {
-                // Passed-in map is itself the name map
-                options.put(OPTION_FUNCTION_MAPPER, new FunctionNameMap(options));
+            if (options.get(OPTION_CLASSLOADER) == null) {
+                options.put(OPTION_CLASSLOADER, interfaceClass.getClassLoader());
             }
             this.options = options;
             this.nativeLibrary = NativeLibrary.getInstance(libname, options);
diff --git a/src/com/sun/jna/Native.java b/src/com/sun/jna/Native.java
index 8b73b1610f..7c83c735cb 100644
--- a/src/com/sun/jna/Native.java
+++ b/src/com/sun/jna/Native.java
@@ -1481,6 +1481,7 @@ else if (cvt[t] == CVT_TYPE_MAPPER) {
         looking them up later.
     */
     private static void cacheOptions(Class cls, Map libOptions, Object proxy) {
+        libOptions = new HashMap(libOptions);
         synchronized(libraries) {
             options.put(cls, libOptions);
             if (proxy != null) {
diff --git a/test/com/sun/jna/NativeTest.java b/test/com/sun/jna/NativeTest.java
index 521774d10a..a946ca8d90 100644
--- a/test/com/sun/jna/NativeTest.java
+++ b/test/com/sun/jna/NativeTest.java
@@ -111,7 +111,7 @@ interface VoidCallback extends Callback {
     }
     public void testSynchronizedAccess() throws Exception {
         final boolean[] lockHeld = { false };
-        final NativeLibrary nlib = NativeLibrary.getInstance("testlib");
+        final NativeLibrary nlib = NativeLibrary.getInstance("testlib", TestLib.class.getClassLoader());
         final TestLib lib = (TestLib)Native.loadLibrary("testlib", TestLib.class);
         final TestLib synchlib = (TestLib)Native.synchronizedLibrary(lib); 
         final TestLib.VoidCallback cb = new TestLib.VoidCallback() {
@@ -168,6 +168,7 @@ public interface TestInterfaceWithInstance extends Library {
         TypeMapper TEST_MAPPER = new DefaultTypeMapper();
         String TEST_ENCODING = "test-encoding";
         Map TEST_OPTS = new HashMap() { {
+            put(OPTION_CLASSLOADER, TestInterfaceWithInstance.class.getClassLoader());
             put(OPTION_TYPE_MAPPER, TEST_MAPPER);
             put(OPTION_STRUCTURE_ALIGNMENT, new Integer(TEST_ALIGNMENT));
             put(OPTION_STRING_ENCODING, TEST_ENCODING);