Index: tests/src/net/sourceforge/stripes/mock/TestMockRoundtrip.java
===================================================================
--- tests/src/net/sourceforge/stripes/mock/TestMockRoundtrip.java	(revision 1133)
+++ tests/src/net/sourceforge/stripes/mock/TestMockRoundtrip.java	(working copy)
@@ -224,4 +224,20 @@
     	request.addHeader("User-Agent", "Netscape/6.0");
     	Assert.assertEquals(request.getHeader("User-Agent"), "Netscape/6.0", MockHttpServletRequest.class + ".addHeader/getHeader do not properly");
     }
+    
+    @Test(groups="fast")
+    public void testAddParameter() throws Exception {
+        // Setup the servlet engine
+        MockServletContext ctx = StripesTestFixture.getServletContext();
+        MockRoundtrip trip = new MockRoundtrip(ctx, TestMockRoundtrip.class);
+        trip.addParameter("param", "a");
+        trip.addParameter("param", "b");
+        trip.execute();
+        
+        TestMockRoundtrip bean = trip.getActionBean(TestMockRoundtrip.class);
+        String[] params = bean.getContext().getRequest().getParameterValues("param");
+        Assert.assertEquals(2, params.length);
+        Assert.assertEquals(new String[] {"a", "b"}, params);
+    }
+    
 }
Index: stripes/src/net/sourceforge/stripes/mock/MockRoundtrip.java
===================================================================
--- stripes/src/net/sourceforge/stripes/mock/MockRoundtrip.java	(revision 1133)
+++ stripes/src/net/sourceforge/stripes/mock/MockRoundtrip.java	(working copy)
@@ -221,6 +221,7 @@
             String[] combined = new String[oldValues.length + value.length];
             System.arraycopy(oldValues, 0, combined, 0, oldValues.length);
             System.arraycopy(value, 0, combined, oldValues.length, value.length);
+            setParameter(name, combined);
         }
     }