diff --git a/build.pl b/build.pl
index c54e52171..177a32529 100755
--- a/build.pl
+++ b/build.pl
@@ -307,6 +307,7 @@ TARGET: lib/go/blobserver/handlers
     - server/go/httputil
     - lib/go/blobserver
     - lib/go/httprange
+    - lib/go/testing
 
 TARGET: lib/go/blobserver/localdisk
     - lib/go/blobref
diff --git a/doc/protocol/blob-enumerate-protocol.txt b/doc/protocol/blob-enumerate-protocol.txt
index 7245fe016..b4d50e471 100644
--- a/doc/protocol/blob-enumerate-protocol.txt
+++ b/doc/protocol/blob-enumerate-protocol.txt
@@ -26,7 +26,8 @@ URL GET parameters:
                            feature), then the server will return
                            immediately if any blobs or available, else
                            it will wait for this number of seconds.
-                           This option isn't supported with 'after'.
+                           It is an error to send this option with a non-
+                           zero value along with the 'after' option.
                            The server's reply must include
                            "canLongPoll" set to true if the server
                            supports this feature.  Even if the server
@@ -35,7 +36,6 @@ URL GET parameters:
                            requested by the client.
 
 
-
 Response:
 
 HTTP/1.1 200 OK
diff --git a/lib/go/blobserver/handlers/enumerate.go b/lib/go/blobserver/handlers/enumerate.go
index 032776ee1..1924aa1e7 100644
--- a/lib/go/blobserver/handlers/enumerate.go
+++ b/lib/go/blobserver/handlers/enumerate.go
@@ -41,15 +41,33 @@ func CreateEnumerateHandler(storage blobserver.Storage, partition blobserver.Par
 	}
 }
 
+const errMsgMaxWaitSecWithAfter = "Can't use 'maxwaitsec' with 'after'.\n"
+
 func handleEnumerateBlobs(conn http.ResponseWriter, req *http.Request, storage blobserver.BlobEnumerator, partition blobserver.Partition) {
-	limit, err := strconv.Atoui(req.FormValue("limit"))
-	if err != nil || limit > maxEnumerate {
-		limit = maxEnumerate
+	// Potential input parameters
+	formValueLimit := req.FormValue("limit")
+	formValueMaxWaitSec := req.FormValue("maxwaitsec")
+	formValueAfter := req.FormValue("after")
+
+	var (
+		err os.Error
+		limit uint
+	)
+	if formValueLimit != "" {
+		limit, err = strconv.Atoui(formValueLimit)
+		if err != nil || limit > maxEnumerate {
+			limit = maxEnumerate
+		}
 	}
 
 	waitSeconds := 0
-	if waitStr := req.FormValue("maxwaitsec"); waitStr != "" {
-		waitSeconds, _ = strconv.Atoi(waitStr)
+	if formValueMaxWaitSec != "" {
+		waitSeconds, _ = strconv.Atoi(formValueMaxWaitSec)
+		if waitSeconds != 0 && formValueAfter != "" {
+			conn.WriteHeader(http.StatusBadRequest)
+			fmt.Fprintf(conn, errMsgMaxWaitSecWithAfter)
+			return
+		}
 		switch {
 		case waitSeconds < 0:
 			waitSeconds = 0
@@ -67,7 +85,7 @@ func handleEnumerateBlobs(conn http.ResponseWriter, req *http.Request, storage b
 	blobch := make(chan *blobref.SizedBlobRef, 100)
 	resultch := make(chan os.Error, 1)
 	go func() {
-		resultch <- storage.EnumerateBlobs(blobch, partition, req.FormValue("after"), limit+1, waitSeconds)
+		resultch <- storage.EnumerateBlobs(blobch, partition, formValueAfter, limit+1, waitSeconds)
 	}()
 
 	after := ""
diff --git a/lib/go/blobserver/handlers/enumerate_test.go b/lib/go/blobserver/handlers/enumerate_test.go
new file mode 100644
index 000000000..0872a3285
--- /dev/null
+++ b/lib/go/blobserver/handlers/enumerate_test.go
@@ -0,0 +1,136 @@
+/*
+Copyright 2011 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package handlers
+
+import (
+	"bufio"
+	"bytes"
+	"camli/blobref"
+	"camli/blobserver"
+	. "camli/testing"
+	"http"
+	"io"
+	"os"
+	"testing"
+)
+
+type responseWriterMethodCall struct {
+	method                 string
+	headerKey, headerValue string // if method == "SetHeader"
+	bytesWritten           []byte // if method == "Write"
+	responseCode           int    // if method == "WriteHeader"
+}
+
+type recordingResponseWriter struct {
+	log    []*responseWriterMethodCall
+	status int
+	output *bytes.Buffer
+}
+
+func (rw *recordingResponseWriter) RemoteAddr() string {
+	return "1.2.3.4"
+}
+
+func (rw *recordingResponseWriter) UsingTLS() bool {
+	return false
+}
+
+func (rw *recordingResponseWriter) SetHeader(k, v string) {
+	rw.log = append(rw.log, &responseWriterMethodCall{method: "SetHeader", headerKey: k, headerValue: v})
+}
+
+func (rw *recordingResponseWriter) Write(buf []byte) (int, os.Error) {
+	rw.log = append(rw.log, &responseWriterMethodCall{method: "Write", bytesWritten: buf})
+	rw.output.Write(buf)
+	if rw.status == 0 {
+		rw.status = 200
+	}
+	return len(buf), nil
+}
+
+func (rw *recordingResponseWriter) WriteHeader(code int) {
+	rw.log = append(rw.log, &responseWriterMethodCall{method: "WriteHeader", responseCode: code})
+	rw.status = code
+}
+
+func (rw *recordingResponseWriter) Flush() {
+	rw.log = append(rw.log, &responseWriterMethodCall{method: "Flush"})
+}
+
+func (rw *recordingResponseWriter) Hijack() (io.ReadWriteCloser, *bufio.ReadWriter, os.Error) {
+	panic("Not supported")
+}
+
+func NewRecordingWriter() *recordingResponseWriter {
+	return &recordingResponseWriter{
+	output: &bytes.Buffer{},
+	}
+}
+
+func makeGetRequest(url string) *http.Request {
+	req := &http.Request{
+        Method: "GET",
+	RawURL: url,
+	}
+	var err os.Error
+	req.URL, err = http.ParseURL(url)
+	if err != nil {
+		panic("Error parsing url: " + url)
+	}
+	return req
+}
+
+type emptyEnumerator struct {
+}
+
+func (ee *emptyEnumerator) EnumerateBlobs(dest chan *blobref.SizedBlobRef,
+        partition blobserver.Partition,
+        after string,
+        limit uint,
+        waitSeconds int) os.Error {
+	dest <- nil
+	return nil
+}
+
+type enumerateInputTest struct {
+	name         string
+	url          string
+	expectedCode int
+	expectedBody string
+}
+
+func TestEnumerateInput(t *testing.T) {
+	enumerator := &emptyEnumerator{}
+
+	emptyOutput := "{\n  \"blobs\": [\n\n  ],\n  \"canLongPoll\": true\n}\n"
+
+	tests := []enumerateInputTest{
+		{"no 'after' with 'maxwaitsec'",
+			"http://example.com/camli/enumerate-blobs?after=foo&maxwaitsec=1", 400,
+			errMsgMaxWaitSecWithAfter},
+		{"'maxwaitsec' of 0 is okay with 'after'",
+			"http://example.com/camli/enumerate-blobs?after=foo&maxwaitsec=0", 200,
+			emptyOutput},
+	}
+	for _, test := range tests {
+		wr := NewRecordingWriter()
+		req := makeGetRequest(test.url)
+		handleEnumerateBlobs(wr, req, enumerator, blobserver.DefaultPartition)
+		ExpectInt(t, test.expectedCode, wr.status, "response code for " + test.name)
+		ExpectString(t, test.expectedBody, wr.output.String(), "output for " + test.name)
+	}
+}
diff --git a/lib/go/testing/testing.go b/lib/go/testing/testing.go
index 1607c9702..ac35b4a0e 100644
--- a/lib/go/testing/testing.go
+++ b/lib/go/testing/testing.go
@@ -34,13 +34,13 @@ func Assert(t *testing.T, got bool, what string) {
 
 func ExpectString(t *testing.T, expect, got string, what string) {
 	if expect != got {
-		t.Errorf("%s: got %v; expected %v", what, got, expect)
+		t.Errorf("%s: got %q; expected %q", what, got, expect)
 	}
 }
 
 func AssertString(t *testing.T, expect, got string, what string) {
 	if expect != got {
-		t.Fatalf("%s: got %v; expected %v", what, got, expect)
+		t.Fatalf("%s: got %q; expected %q", what, got, expect)
 	}
 }